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Economics

Paying for War: Taxes, Borrowing, Money Printing and Aid

The United States paid for the First World War with about 58% borrowing from the public, 22% taxes and about 20% money creation, according to economic historian Hugh Rockoff.

Key figures at a glance
  • The United States paid for the First World War with about 58% borrowing from the public, 22% taxes and about 20% money creation, according to economic historian Hugh Rockoff.[3]
  • UK government debt rose from 27.9% of GDP in 1913 to 269.8% in 1946, after two world wars.[2]
  • US war spending peaked at 35.8% of GDP in 1945, against 2.3% at the peak of the Vietnam War in 1968.[6]
  • The US post-9/11 wars cost about $5.8 trillion to FY2022, including $1.09 trillion of interest on borrowing, because they were paid for by debt rather than a war tax.[10]
  • Foreign governments allocated €383 billion of military, financial and humanitarian aid to Ukraine between January 2022 and August 2026.[8]
  • Russia’s National Wealth Fund liquid assets fell from about 9.8 trillion roubles in February 2022 to about 3.7 trillion at end-July 2026.[14][18]
  • Israel moved from a budget surplus of 0.6% of GDP in 2022 to a deficit of 6.8% in 2024.[21][20]

Chapter 1 showed how war damages an economy. This chapter asks how governments pay for it. There are only four sources of money: taxes, borrowing, printing money and help from abroad. Every war in this book used some mix of them. The mix matters, because each source passes the cost to a different group of people: today’s taxpayers, tomorrow’s taxpayers, savers whose money loses value, or foreign governments.

1. Background: the four ways to pay

A government at war faces a sudden, large rise in spending. It can:

  1. Raise taxes. The cost falls on people now, in the open.
  2. Borrow from its own citizens, banks or foreign lenders. The cost falls on future taxpayers, who must pay interest and repay the debt.
  3. Print money, by having the central bank finance the government. The cost falls on anyone holding money or fixed-income assets, through inflation. Economists call this the inflation tax.
  4. Receive aid or loans from allies. The cost falls, at least in part, on foreign taxpayers.

The table below lists the episodes covered in this chapter.

DateEpisode
Nov 1914UK’s first War Loan raises far less than its £350 million target; the Bank of England secretly buys the shortfall.[1]
1917–1919US finances the First World War with Liberty Bonds, higher taxes and money creation.[3]
1922–1923German hyperinflation; stabilised in November 1923.[9]
Dec 1940Roosevelt proposes Lend-Lease; about $50 billion of aid follows.[7]
1941–1945US and UK debt soars; the US uses a “mass tax”, war bonds and low interest rates.[5]
1950–1953Korean War paid for mainly by taxes and cuts to other spending.[5]
1965–1975Vietnam War mostly deficit-financed; 10% tax surcharge in 1968–69.[5]
1990–1991Gulf War: allies contribute $48 billion of a $61 billion cost.[5]
2001–2022US post-9/11 wars financed by borrowing.[10]
2022–2026Ukraine relies on foreign aid; Russia draws down its wealth fund and raises taxes; Israel borrows.[8][15][20]

2. Where things stand now

As of October 2026, three governments discussed in this book face the heaviest war-finance burdens.

Ukraine spent $84.1 billion on its military in 2025, equal to 40% of GDP, according to SIPRI.[12] Its general government deficit was 17.6% of GDP in 2025 and its gross debt 107.1% of GDP, according to IMF data.[11] The gap is filled largely by foreign help. The Kiel Institute’s tracker, updated on 8 October 2026, records €383 billion of aid allocated to Ukraine from January 2022 to August 2026.[8][31] The European Union pledged a €90 billion Ukraine Support Loan, recorded in December 2025 and formally approved in April 2026.[8]

Russia spent $190 billion on its military in 2025, 7.5% of GDP.[12] It raised its main VAT rate to 22% from January 2026.[15] Even so, Finland’s central bank research unit (BOFIT) reports that the federal deficit for 2026 is expected to reach 8.6 trillion roubles, or 4% of GDP, a record.[19]

Israel recorded a deficit of 4.7% of GDP in 2025, after 6.8% in 2024.[22][20] The IMF projects public debt of 70.1% of GDP in 2026.[24]

3. The economy before the war: why fiscal space matters

Fiscal space is the room a government has to raise spending or cut taxes without putting its finances at risk. A country that enters a war with low debt, a credible central bank and deep financial markets can borrow more, for longer and at lower interest rates. A country without these must rely more on printing money or on foreign help.

Country, year before warGovernment debt, % of GDP
United Kingdom, 191327.9[2]
United States, 194042.4[2]
Ukraine, 202148.9[11]
Russia, 202116.5[11]
Israel, 202260.9[11]

Low debt is not the only thing that matters. Russia entered its war with very low debt and a large savings buffer, the National Wealth Fund, which it has since run down (Section 4.6).[14] Ukraine entered with moderate debt, but its military spending rose to around 40% of GDP, far beyond what borrowing at home could cover, so foreign aid became essential (Section 4.5).[12][8]

4. The four tools in practice: case by case

4.1 Taxes

Taxes are the most transparent way to pay. They also make the cost of war visible to voters. In large wars, however, they rarely cover more than a minority of the cost.

In the First World War, UK government spending rose more than twelve-fold, to £2.37 billion, between 1913/14 and 1918/19. Tax revenue quadrupled, but war debt covered the rest.[1] In the United States, taxes and other receipts paid for about 22% of the war from March 1917 to May 1919. Tax rates rose steeply: the effective income tax rate on a $1 million income rose from 6.0% to 70.3% in 1918, and a new excess-profits tax of 20% to 60% was introduced.[3]

In the Second World War, the US Revenue Act of 1942 created what was called a “mass tax”, bringing many more households into income tax, and a 90% excess-profits tax.[5] The Korean War stands out as the one large US war paid for mainly by taxes: the Revenue Acts of 1950 and 1951 raised taxes by about 1.3% and 1.9% of GDP, and non-military spending was cut. Deficits were much lower than in any other war the Congressional Research Service studied.[5]

Today, Russia offers the clearest example of a tax rise to pay for war. Its main VAT rate rose by two percentage points to 22% in 2026.[15] In January–July 2026, VAT revenue was 25% higher than a year earlier, while oil and gas revenue fell 17%.[18]

4.2 Borrowing

Borrowing spreads the cost of war over many years. In both world wars, it was the main source of finance for the United Kingdom and the United States. Chart 1 shows the result for government debt.

Government debt in the world wars: UK and US, 1913–1950 (% of GDP)
United KingdomUnited States
050100150200250300%1913191619191929194019441946
Source: IMF Historical Public Debt Database (Public Finances in Modern History) [2] Gross public debt. US series in this database starts in 1929. Uneven spacing of years.

UK debt rose from about 25% of GDP to about 125% in the four years of the First World War.[1] It peaked at 269.8% of GDP in 1946, after the Second World War. US debt reached 121.2% of GDP in 1946.[2] Measured as debt held by the public, the US figure was 108.6% of GDP in 1946.[5] The two figures differ because they use different definitions of debt.

Governments sold war bonds directly to savers. In the US, every Liberty Bond issue of the First World War was oversubscribed, and war debt reached $26.4 billion by August 1919.[3] Patriotism did not always work, however. The UK’s first War Loan in November 1914 aimed to raise £350 million, but the public bought only £91.1 million. To hide the failure, the Bank of England lent money to its Chief Cashier and his deputy, who bought the bonds in their own names. The Bank recorded these as “other securities” rather than government securities.[1]

The US post-9/11 wars were financed almost entirely by borrowing. The Costs of War project at Brown University notes that there was no war tax and no mass sale of war bonds. The US moved from a balanced budget in 2001 to deficits from 2002. By FY2022, the wars had cost about $5.8 trillion, of which about $1.09 trillion was interest on the money borrowed. Including future veterans’ care, the total rises to about $8 trillion.[10] The Congressional Research Service notes that the Iraq War was at first entirely deficit-financed, alongside a 2003 tax cut.[5]

US war costs at their peak year (war cost as % of GDP in peak year)
010203040% of GDPCivil War (Union, 1865)WWI (1919)WWII (1945)Korea (1952)Vietnam (1968)Gulf War (1991)Post-9/11 (2008)11.313.635.84.22.30.31.2
Source: Congressional Research Service, Costs of Major U.S. Wars (RS22926), 2010 [6] Direct war costs only, excluding the regular defence budget.

Chart 2 puts these wars in proportion. At their peak, US war costs reached 13.6% of GDP in the First World War and 35.8% in the Second, but only 2.3% in Vietnam and 1.2% for the post-9/11 wars.[6] Smaller wars can be financed by borrowing without a crisis, but the interest bill still adds up.

Common mistake Borrowing does not make a war free. It moves the cost to future taxpayers, who pay interest and principal. In the post-9/11 case, interest alone had reached about $1.09 trillion by FY2022.

4.3 Printing money and the inflation tax

When a central bank buys government bonds with newly created money, the government can spend without raising taxes or finding private lenders. The cost appears later as inflation, which reduces the real value of money and bonds held by the public.

About 20% of the US First World War effort was financed by money creation, according to Rockoff: about 5% directly and about 15% indirectly through commercial banks. He notes that the second figure is an upper bound. The Federal Reserve held a large share of the new debt.[3] US consumer prices rose 17.8% in 1917 and 17.3% in 1918.[4]

In the Second World War, the US Treasury and the Federal Reserve kept interest rates on government bonds artificially low. This required rapid money creation, mainly through Fed purchases of government bonds. Rationing and price controls held down measured inflation during the war, but prices jumped once controls ended. An “accord” between the Treasury and the Fed in 1951 ended the arrangement.[5] US consumer prices rose 10.9% in 1942 and 14.4% in 1947, after controls were lifted.[4]

Germany, 1922–23: the extreme case. Germany’s public finances after the First World War were dominated by reparations, the payments the Allies demanded. Thomas Sargent describes how the uncertain total “cast a long shadow” over the currency. After France occupied the Ruhr in January 1923, the government paid striking workers by having the central bank, the Reichsbank, discount treasury bills. By October 1923 it was financing virtually 100% of its spending by printing money. Wholesale prices rose about 2,000-fold between January 1922 and July 1923.[9]

The hyperinflation ended in late November 1923. A new currency, the Rentenmark, was set at 1 trillion paper marks, and note issue to the government was capped. Sargent argues that the key change was fiscal, not the new currency: government borrowing from the central bank stopped “simultaneously and abruptly”, the budget moved towards balance and reparations were later rescheduled under the Dawes Plan.[9]

Vietnam and the Great Inflation. The Vietnam War was much smaller relative to the US economy, but it was mostly financed by deficits. Tax increases came late, near the peak of the war, with temporary 10% surcharges on personal and corporate income tax in 1968 and 1969.[5] US inflation rose from 1.6% in 1965 to 5.8% in 1970 (Chart 3).[4] President Nixon later imposed price controls in four phases.[5] The war was not the only cause of the high inflation of the 1970s, and this chapter does not try to separate the causes. But it shows how a “guns and butter” policy, raising military and civilian spending at the same time without matching taxes, can add to demand in an economy close to full capacity.

US consumer price inflation, 1960–1980 (% change in annual average CPI)
02.557.51012.515%19601962196419661968197019721974197619781980
Source: US BLS CPI-U (CPIAUCNS) via FRED, author's calculation; CRS [4][6] CRS dates the Vietnam War 1965–1975. The chart does not separate the war's effect from other causes of inflation.
Key term: inflation tax When the government finances spending by creating money, the resulting inflation reduces the real value of money and fixed-income assets held by the public. This transfer of purchasing power from the public to the government works like a tax, even though no law imposes it. The revenue the government gains from creating money is called seigniorage.

4.4 Foreign aid and loans

Help from allies can be decisive for a country fighting a much larger enemy.

Lend-Lease. President Roosevelt proposed Lend-Lease in December 1940. More than 30 countries signed Lend-Lease agreements, and the US provided about $50 billion of aid over the war. Payment was deferred, and in Britain’s case was mainly to take the form of joint action towards a more open world economy after the war.[7] The Kiel Institute estimates that US Lend-Lease to the UK averaged about 3.2% of US GDP a year in 1941–45, far more than any donor’s military aid to Ukraine in 2022–23 (Chart 4).[8]

Military aid then and now: average per year (% of donor GDP per year)
01234% of donor GDPUS to UK, 1941–45US to USSR, 1941–45UK to USSR, 1941–45US to France, 1944–45UK to Ukraine, 2022–23US to Ukraine, 2022–233.21.40.820.360.20.19
Source: Kiel Institute, Ukraine Support Tracker (historical comparison) [8] Second World War figures are Lend-Lease. Ukraine figures cover military aid from February 2022 to February 2023.

The Gulf War. In 1990–91, allied governments contributed $48 billion towards a US war cost of $61 billion.[5] This is the clearest modern case of a war paid for largely by others.

Ukraine. Foreign aid has been central to Ukraine’s war finance. Chart 5 shows cumulative aid allocations by type, as recorded by the Kiel Institute. By August 2026, military aid reached €186.5 billion, financial aid €170.7 billion and humanitarian aid €26.2 billion.[8]

Aid allocated to Ukraine by type, cumulative (€ billion)
MilitaryFinancialHumanitarian
050100150200€ bnEnd-2022End-2023End-2024End-2025Aug 2026
Source: Kiel Institute, Ukraine Support Tracker, release of October 2026 [8] Government-to-government aid from 41 countries plus EU institutions, from 24 January 2022. Excludes IMF and World Bank lending.

The source of aid has shifted. Total US allocations recorded by Kiel stood at €115.4 billion in January 2025 and had not risen by August 2026. European allocations, including the EU institutions, rose from €134.7 billion to €236.9 billion over the same period.[8]

The type of financial aid matters too. Of the €170.5 billion of financial aid in Kiel’s breakdown by donor, it records €64.7 billion of ordinary loans, €41.9 billion of grants, €21.8 billion of guarantees and €41.3 billion of Extraordinary Revenue Acceleration (ERA) loans.[8] The ERA scheme, agreed by the G7, is designed to raise $50 billion for Ukraine, to be serviced from the earnings on immobilised Russian central bank assets.[8] Loans must eventually be repaid, which is one reason Ukraine’s debt has risen so fast. Grants do not add to debt.

4.5 Ukraine, 2022–2026: a war financed from abroad

Ukraine’s military spending rose from about 3.4% of GDP in 2021 to about 39.6% in 2025.[13] No government can raise taxes by that much during a war in which its economy shrank 28.8% in a single year.[11] The result was very large deficits: 15.6% of GDP in 2022, 19.3% in 2023, 17.2% in 2024 and 17.6% in 2025, according to the IMF (Chart 6).[11]

Government budget balance, 2021–2026 (% of GDP (general government))
UkraineRussiaIsrael
-20-15-10-505% of GDP202120222023202420252026*
Source: IMF World Economic Outlook database (DataMapper, accessed Oct 2026) [11] *2026 IMF projection. IMF general government data; national figures differ (e.g. Israel central government deficit 6.8% in 2024; Russia federal deficit 2.6% in 2025).

Gross public debt more than doubled, from 48.9% of GDP in 2021 to 107.1% in 2025, and the IMF projects 111.8% in 2026 (Chart 7).[11] Ukraine also owed the IMF itself SDR 10.9 billion at the end of March 2026. (The SDR, or special drawing right, is the IMF’s unit of account.)[30] Inflation averaged 20.2% in 2022 and 12.7% in 2025.[11] The hryvnia weakened from 27.3 per dollar on average in 2021 to 41.7 in 2025.[29] On top of war spending, Ukraine faces reconstruction needs of almost $588 billion over the next decade.[28]

Gross government debt, 2021–2026 (% of GDP)
UkraineRussiaIsrael
020406080100120% of GDP202120222023202420252026*
Source: IMF World Economic Outlook database (DataMapper, accessed Oct 2026); IMF [11][24] *2026 IMF projection. The IMF's July 2026 Article IV for Israel projects 70.1% for 2026.

4.6 Russia, 2022–2026: drawing down savings and raising taxes

Russia’s war budget has been financed by three means: running down savings, raising taxes and, increasingly, borrowing at home.[14][15][18]

Spending. Military spending rose from 3.6% of GDP in 2021 to 7.5% in 2025.[13] The draft 2027 budget plans about 17 trillion roubles (about $200 billion) for defence, nearly five times the 2021 level. Defence and national security together would take about 23% of consolidated government spending.[19]

Savings. Russia’s National Wealth Fund (NWF) is a reserve fund built from past oil and gas revenue. Its liquid assets fell from about 9.8 trillion roubles in February 2022 to about 3.8 trillion at the end of 2024.[14] They stood at 4.2 trillion roubles (2% of GDP) at the end of September 2025 and about 3.7 trillion at the end of July 2026.[15][18]

Russia: federal budgetDeficitSource
2024About 3.5 trillion roubles (1.7% of GDP)BOFIT[14]
20255.6 trillion roubles (2.6% of GDP)BOFIT[16]
Jan–Jul 20266.5 trillion roubles (nearly 3% of GDP)BOFIT[18]
2026 (expected)8.6 trillion roubles (4% of GDP)BOFIT[19]
2027 (draft budget)6.5 trillion roubles (2.6% of GDP)BOFIT[19]

Forecasts have often been too optimistic. In October 2025, the 2026 deficit was planned at 3.8 trillion roubles (1.6% of GDP).[15] By October 2026, it was expected to be more than twice as large.[19]

Borrowing. Most of the 2026 shortfall is to be covered by issuing more debt. A law signed in late June 2026 allowed the government to borrow more this year, but it recently struggled to find buyers at a government bond auction.[18] Russia’s general government debt remains low by international standards, at 16.6% of GDP in 2025, but the IMF projects 22.2% by 2027.[11]

Inflation and interest rates. Consumer prices rose 9% on average in 2025. The central bank’s key interest rate was at a record 21% at the end of 2024 and 16% at the end of 2025.[14][16] It was cut to 14.25% in June 2026.[17] High interest rates have helped to stop war spending turning into runaway inflation, but they raise the cost of credit for civilian firms.

4.7 Israel, 2023–2026: borrowing on the strength of low debt

Israel entered the war that began on 7 October 2023 in a strong fiscal position. It ran a budget surplus of 0.6% of GDP in 2022, its first since 1987.[21] Public debt was about 60% of GDP.[20]

War spending was large. Reuters reported that war-related spending in 2024 was about NIS 100 billion (about $28 billion), out of total government spending of NIS 621 billion.[25] In January 2026, the Ministry of Finance put the direct cost of the war since October 2023 at about NIS 199 billion, of which about NIS 164 billion was defence.[22] The Bank of Israel’s earlier estimate, from September 2024, was about NIS 250 billion of military and civilian costs for 2023–25.[20] The estimates differ in their coverage and timing. The 2026 war with Iran added a preliminary NIS 35 billion (about $11.5 billion) in budget costs, of which NIS 22 billion was defence, according to the Ministry of Finance.[26]

Israel financed this mainly by borrowing. The central government deficit rose from about 4.0–4.1% of GDP in 2023 (the State Comptroller’s report gives both figures) to 6.8% in 2024, before falling to an initial 4.7% in 2025.[20][22] Public debt rose to 67.7% of GDP in 2024 and an initial 68.6% in 2025.[23] In February 2024, Moody’s downgraded Israel’s credit rating for the first time, from A1 to A2.[27] In March 2026, the defence budget for 2026 was raised from about NIS 111 billion to about NIS 140 billion, and the deficit target to 5.1% of GDP.[32]

5. What went well and what went wrong

What went well

  • Korea, 1950–53: paying mainly through taxes and spending cuts kept deficits much lower than in other US wars.[5]
  • Lend-Lease: deferred payment let Britain keep fighting without an immediate dollar debt.[7]
  • Gulf War: allied contributions covered most of the US cost.[5]
  • Germany, November 1923: ending central bank financing of the deficit stopped hyperinflation almost at once.[9]
  • Israel, 2022: entering the war with a budget surplus gave room to borrow; debt rose by about 8 percentage points of GDP between 2022 and 2025 rather than spiralling.[20][21][23]
  • Ukraine: large grants and long-term loans from abroad have financed deficits of 15–19% of GDP a year.[8][11]

What went wrong

  • UK, 1914: the first War Loan failed to attract the public, and the Bank of England hid its own purchases.[1]
  • Germany, 1923: printing money to cover nearly all spending destroyed the currency.[9]
  • US, 1940s: price controls suppressed inflation during the war, but prices rose 14.4% in 1947 after controls ended.[4]
  • Vietnam: late and temporary tax rises left the war mostly deficit-financed as inflation climbed.[5][4]
  • Post-9/11: borrowing without a war tax added about $1.09 trillion of interest costs by FY2022.[10]
  • Russia: the wealth fund has been run down, and deficits have repeatedly exceeded plans.[14][19]
  • Ukraine: heavy reliance on loans has pushed debt above 100% of GDP, which will constrain reconstruction.[11]

6. The economics behind it

Opportunity cost and who pays. However a war is financed, real resources are used up while it is fought: steel, fuel, labour. Finance decides who bears that cost and when. Taxes make today’s taxpayers pay. Borrowing from citizens means today’s savers lend their resources and are repaid by tomorrow’s taxpayers. Foreign borrowing and aid let a country use other countries’ resources now. Printing money takes resources from holders of money through inflation.

Tax smoothing. Many economists argue that a government should not raise tax rates sharply during a short war and cut them after. High tax rates discourage work and investment, and the damage rises faster than the rate. It can be better to borrow during the war and raise taxes moderately over many years to repay. This helps explain why borrowing dominated in both world wars. But a long war, or one fought from a weak fiscal position, cannot be financed by borrowing alone.

Crowding out. Heavy government borrowing competes with private firms for savings. This can push up interest rates and reduce private investment. In the Second World War, the US avoided rising rates by keeping bond yields artificially low, which required money creation.[5] In Russia today, the central bank has kept interest rates high to fight inflation, which raises the cost of credit for civilian firms.[14][17]

Diagram Draw a loanable funds diagram with the real interest rate on the vertical axis and the quantity of loanable funds on the horizontal axis. Government war borrowing shifts the demand for loanable funds to the right. The equilibrium interest rate rises, and the quantity of private investment falls along the original demand curve: this is crowding out. Now show a central bank buying government bonds with new money: the supply of loanable funds shifts right, holding the interest rate down, but the money supply rises, adding to inflation.

The quantity theory and hyperinflation. The quantity theory of money links the money supply (M), the speed at which money circulates (V), the price level (P) and real output (Y): MV = PY. When a war government prints money while output falls, P must rise. If people expect further inflation, they spend money faster, so V rises too, and inflation accelerates. This is what happened in Germany in 1923.[9]

Diagram Use an AD/AS diagram. Military spending financed by new money shifts AD to the right (AD1 to AD2). If the economy is close to full capacity, the extra demand raises the price level more than output. If war also shifts SRAS to the left, through lost workers or shortages, the price level rises further. Compare this with tax-financed spending, which reduces private consumption and so shifts AD right by less.

Debt dynamics. Whether war debt can be managed depends on the gap between the interest rate on debt (r) and the economy’s growth rate (g). If g is higher than r, the debt ratio can fall even with small deficits. The UK’s debt ratio fell from 269.8% of GDP in 1946 to 117.9% in 1960 and 73.4% in 1970 without any default.[2] If r is higher than g, debt grows unless the government runs primary surpluses (surpluses before interest payments).

Exam tip When asked how a war “should” be financed, do not give a single answer. Compare at least two methods using criteria: effect on inflation, effect on interest rates and investment, who bears the cost, and whether the method is sustainable for a long war. Then judge, using a historical example for each side.

7. Outlook and the way forward

Ukraine. Financing for 2026–27 depends heavily on the EU’s €90 billion Ukraine Support Loan, approved in April 2026. The European Commission had begun disbursements, including a first macro-financial tranche of €3.2 billion and €3.47 billion under the loan’s defence window.[8] The IMF projects the deficit to narrow to 11.3% of GDP in 2026 and 2.9% in 2027, a forecast that assumes war spending falls sharply.[11] If the war continues, that path is unlikely. Reconstruction needs of almost $588 billion will require large grants and private investment, not only loans, if debt is not to rise further.[28]

Russia. The 2027 draft budget plans a smaller deficit (2.6% of GDP) and assumes an oil price of $53 a barrel, with oil and gas providing only 16% of federal revenue.[19] With the wealth fund’s liquid assets down to about 3.7 trillion roubles, future deficits will need to be covered mainly by domestic borrowing or further tax rises.[18] BOFIT forecasts growth of only about 0.5% in 2027.[19]

Israel. The IMF projects public debt of 70.1% of GDP in 2026.[24] Higher defence spending is likely to persist, as the 2026 budget shows.[32] The main risks are renewed fighting and the cost of servicing a higher debt.

Europe and the world. World military spending rose for an 11th year in 2025, and European spending rose 14%.[12] Many governments will face the same choices discussed in this chapter, in peacetime: raise taxes, cut other spending or borrow more.

The historical lesson is consistent. Wars that are short, or fought from strong fiscal positions, can be financed by borrowing. Long wars require taxes, foreign help or both. Printing money is the easiest route in the short run and the most damaging in the long run.

8. Exam-style questions

MediumQ1. Explain what is meant by the “inflation tax” and give one historical example. Show answer guide
The inflation tax is the loss of purchasing power suffered by holders of money and fixed-income assets when a government finances spending by creating money. The government gains real resources (seigniorage) without legislating a tax. Examples: about 20% of US First World War finance came from money creation, with consumer prices rising 17.8% in 1917; or Germany in 1923, when almost all spending was financed by the Reichsbank and prices rose about 2,000-fold in 18 months.
MediumQ2. Using a loanable funds diagram, explain how government borrowing to finance a war may crowd out private investment. Show answer guide
Show demand for loanable funds shifting right as the government borrows; the real interest rate rises and private investment falls. Note that the effect can be offset if savings rise (patriotic saving, war bonds) or if the central bank holds rates down, as in the US in the 1940s, but the latter adds to the money supply and inflation. Russia’s high key rate (21% at end-2024) is a modern example of high borrowing costs for civilian firms.
HardQ3. Compare the way Ukraine and Russia have financed their military spending since 2022. Show answer guide
Ukraine: military spending of about 40% of GDP, deficits of 15–19% of GDP, financed mainly by foreign aid (€383 billion allocated by August 2026, including €170.7 billion financial aid, much of it loans), so debt rose from 48.9% to 107.1% of GDP. Russia: military spending of 7.5% of GDP, smaller deficits (2.6% of GDP federal in 2025), financed by drawing down the National Wealth Fund (9.8 to about 3.7 trillion roubles), raising VAT to 22% and domestic borrowing; debt is low but rising. Conclude on sustainability: Ukraine depends on donors’ political will; Russia on oil prices and domestic savers.
ExamQ4. Evaluate whether borrowing is a better way than taxation to finance a war. Show answer guide
For borrowing: spreads costs over time (tax smoothing); avoids high tax rates that discourage work during mobilisation; the UK and US borrowed most of the cost of both world wars and later reduced debt ratios through growth (UK from 269.8% of GDP in 1946 to 73.4% by 1970). Against: interest costs (about $1.09 trillion for the US post-9/11 wars by FY2022); crowding out; risk of turning into money printing if lenders refuse (Germany 1923; the 1914 UK War Loan shortfall); hides the true cost from voters. Taxation: transparent and avoids debt (Korea), but limited in very large wars and can depress output. A strong answer concludes that the best mix depends on the war’s size and length, pre-war debt, credibility of institutions and access to foreign help.

Glossary

  • Fiscal space: room for a government to raise spending or cut taxes without endangering its finances.
  • Budget deficit: the amount by which government spending exceeds revenue in a year.
  • Public debt: the total stock of money the government owes, built up from past deficits.
  • War bonds: government bonds sold to the public to finance a war.
  • Inflation tax: the loss of purchasing power on money and fixed-income assets when the government finances spending by creating money.
  • Seigniorage: the revenue a government gains from creating money.
  • Hyperinflation: extremely rapid and accelerating inflation that destroys confidence in a currency, as in Germany in 1923.
  • Crowding out: a fall in private investment caused by government borrowing pushing up interest rates.
  • Tax smoothing: keeping tax rates fairly stable over time and borrowing to cover temporary spending peaks.
  • Sovereign wealth fund: a state-owned fund that invests national savings, such as Russia’s National Wealth Fund.
  • Lend-Lease: the US programme of 1941–45 that supplied allies with war materials, with payment deferred.
  • Primary balance: the budget balance excluding interest payments on debt.

References

  1. Anson, M., Cohen, N., Owens, A. and Todman, D. (2017). “Your country needs funds: the extraordinary story of Britain’s early efforts to finance the First World War”. Bank Underground (Bank of England staff blog), 8 August 2017. https://bankunderground.co.uk/2017/08/08/your-country-needs-funds-the-extraordinary-story-of-britains-early-efforts-to-finance-the-first-world-war/
  2. IMF (2026). “Gross public debt, percent of GDP”, Public Finances in Modern History / Historical Public Debt Database, via IMF DataMapper. Accessed 14 October 2026. https://www.imf.org/external/datamapper/api/v1/d/GBR/USA
  3. Rockoff, H. (2004). “Until It’s Over, Over There: The U.S. Economy in World War I”. NBER Working Paper 10580, June 2004. https://www.nber.org/system/files/working_papers/w10580/w10580.pdf
  4. US Bureau of Labor Statistics (2026). “Consumer Price Index for All Urban Consumers: All Items in U.S. City Average (CPIAUCNS)”, annual averages, via FRED, Federal Reserve Bank of St. Louis. Accessed 14 October 2026; annual inflation rates calculated by the author. https://fred.stlouisfed.org/series/CPIAUCNS
  5. Congressional Research Service (2008). “Financing Issues and Economic Effects of American Wars” (RL31176). CRS, updated 29 July 2008. https://www.everycrsreport.com/reports/RL31176.html
  6. Congressional Research Service (2010). “Costs of Major U.S. Wars” (RS22926). CRS, 29 June 2010. https://www.everycrsreport.com/reports/RS22926.html
  7. Office of the Historian, US Department of State. “Lend-Lease and Military Aid to the Allies in the Early Years of World War II”. Milestones in the History of U.S. Foreign Relations. https://history.state.gov/milestones/1937-1945/lend-lease
  8. Kiel Institute for the World Economy (2026). “Ukraine Support Tracker”, data release 31 (aid to 31 August 2026), October 2026. https://www.kielinstitut.de/publications/ukraine-support-tracker-data-6453/
  9. Sargent, T. J. (1982). “The Ends of Four Big Inflations”. In R. E. Hall (ed.), Inflation: Causes and Effects, University of Chicago Press / NBER, pp. 41–98. https://www.nber.org/system/files/chapters/c11452/c11452.pdf
  10. Crawford, N. C. (2021). “The U.S. Budgetary Costs of the Post-9/11 Wars”. Costs of War Project, Watson Institute, Brown University, 1 September 2021. https://costsofwar.watson.brown.edu/sites/default/files/papers/Costs-of-War_US-Budgetary-Costs-of-Post-9-11-Wars.pdf
  11. IMF (2026). World Economic Outlook database via IMF DataMapper: general government net lending/borrowing, gross debt, inflation and real GDP growth. Accessed 14 October 2026. https://www.imf.org/external/datamapper/GGXCNL_NGDP@WEO
  12. SIPRI (2026). “World Military Expenditure 2025” (fact sheet). Stockholm International Peace Research Institute, April 2026. https://www.sipri.org/sites/default/files/Military%20Expenditure%202025.pdf
  13. World Bank (2026). “Military expenditure (% of GDP)”, World Development Indicators, series MS.MIL.XPND.GD.ZS (source: SIPRI). Accessed 14 October 2026. https://api.worldbank.org/v2/country/WLD;UKR;RUS;USA;ISR/indicator/MS.MIL.XPND.GD.ZS?date=2014:2025&format=json
  14. BOFIT (2025). “Russian economic output growth slowed and economic imbalances worsened in second half of 2024”. BOFIT Weekly Review 5/2025, Bank of Finland, 31 January 2025. https://www.bofit.fi/en/monitoring/weekly/2025/vw202505_1/
  15. BOFIT (2025). “Russia’s new budget framework does not promise support for fading economic growth”. BOFIT Weekly Review 41/2025, Bank of Finland, 10 October 2025. https://www.bofit.fi/en/monitoring/weekly/2025/vw202541_1/
  16. BOFIT (2026). “Russian economy lost steam in 2025”. BOFIT Weekly Review 7/2026, Bank of Finland, 13 February 2026. https://www.bofit.fi/en/monitoring/weekly/2026/vw202607_1/
  17. BOFIT (2026). “Russia faces increasing challenges in balancing its economic policies”. BOFIT Weekly Review 27/2026, Bank of Finland, 3 July 2026. https://www.bofit.fi/en/monitoring/weekly/2026/vw202627_1/
  18. BOFIT (2026). “Higher oil prices boost Russia’s export earnings, but fiscal deficit widens”. BOFIT Weekly Review 33/2026, Bank of Finland, 14 August 2026. https://www.bofit.fi/en/monitoring/weekly/2026/vw202633_1/
  19. BOFIT (2026). “Russia’s growth slows further, government finances remain in the red”. BOFIT Weekly Review 41/2026, Bank of Finland, 9 October 2026. https://www.bofit.fi/en/monitoring/weekly/2026/vw202641_1/
  20. State Comptroller of Israel (2025). Annual report on financial and budgetary matters 2025 (report 102). Office of the State Comptroller, October 2025. https://library.mevaker.gov.il/sites/DigitalLibrary/Documents/2025/2025-Financial-and-Budgetary/EN/2025-Financial-and-Budgetary-102-Taktzir-EN.pdf
  21. Globes (2023). “Israel posts first budget surplus since 1987”. Globes, 11 January 2023. https://en.globes.co.il/en/article-1001435230
  22. Globes (2026). Israel’s 2025 budget deficit and the cost of the war. Globes, 13 January 2026. https://en.globes.co.il/en/article-1001531862
  23. Israel Ministry of Finance (2026). Press release on public debt, 25 January 2026. https://www.gov.il/BlobFolder/news/press_25012026/en/PressReleases_eng_press_25012026-en-file.pdf
  24. IMF (2026). “Israel: IMF Executive Board Concludes 2026 Article IV Consultation”. Press release PR26/234, 1 July 2026. https://imf.org/en/news/articles/2026/07/01/pr26234-israel-imf-executive-board-concludes-2026-article-iv-consultation
  25. Reuters (2025). “Israel’s war spending in 2024 lifts deficit”. Reuters via Yahoo News, January 2025. https://www.yahoo.com/news/israels-war-spending-2024-lifts-122051510.html
  26. Al Arabiya / Reuters (2026). “Iran war has cost Israel $11.5 billion in budgetary expenses, ministry says”. Al Arabiya, 12 April 2026. https://english.alarabiya.net/News/middle-east/2026/04/12/iran-war-has-cost-israel-115-billion-in-budgetary-expenses-ministry-says
  27. Globes (2024). “Moody’s downgrades Israel’s credit rating”. Globes, 9 February 2024. https://en.globes.co.il/en/article-1001470867
  28. World Bank (2026). “Updated Ukraine Recovery and Reconstruction Needs Assessment Released” (RDNA5). Press release, 23 February 2026. https://www.worldbank.org/en/news/press-release/2026/02/23/updated-ukraine-recovery-and-reconstruction-needs-assessment-released
  29. World Bank (2026). “Official exchange rate (LCU per US$, period average)”, World Development Indicators, series PA.NUS.FCRF. Accessed 14 October 2026. https://api.worldbank.org/v2/country/UKR;RUS/indicator/PA.NUS.FCRF?date=2020:2025&format=json
  30. IMF (2026). “Ukraine” country page: financial position in the Fund (as of 31 March 2026). Accessed 14 October 2026. https://www.imf.org/en/Countries/UKR
  31. Kiel Institute for the World Economy (2026). “Ukraine Support Tracker” (project page, update of 8 October 2026). https://www.kielinstitut.de/research/topics/war-against-ukraine/ukraine-support-tracker
  32. Globes (2026). Israel raises 2026 defence budget and deficit target. Globes, 11 March 2026. https://en.globes.co.il/en/article-1001537235
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