Fiscal Policy

Expansionary and Contractionary Fiscal Policy

On March 27, 2020, President Trump signed the Coronavirus Aid, Relief, and Economic Security Act into law. The price tag was $2.2 trillion, the largest single economic rescue package in American history at that point. Within weeks, the Treasury Department began depositing $1,200 checks into the bank accounts of roughly 160 million Americans. Airlines received $25 billion in payroll grants. Hospitals got $175 billion. Small businesses could apply for forgivable loans through the Paycheck Protection Program, which ultimately distributed $800 billion across two rounds. The logic was blunt: the economy had lost 22 million jobs in March and April, GDP was contracting at an annualized rate of 31.4% in the second quarter, and Congress decided that massive federal spending was the only lever large enough to prevent a depression. That spending was fiscal policy in its rawest form, the federal government using its taxing and spending authority to shift aggregate demand when the private sector could not or would not spend.

Expansionary fiscal policy targets a recessionary gap. The government can increase spending (G), cut taxes (T), or do both simultaneously, and each approach shifts AD to the right, raising both real GDP and the price level. Nine years before the CARES Act, Congress had deployed the same playbook during the Great Recession. The American Recovery and Reinvestment Act of 2009 injected $831 billion into the economy through a mix of infrastructure projects, state fiscal relief, and middle-class tax cuts.

Contractionary fiscal policy operates in reverse. An economy running past its potential output, producing an inflationary gap, theoretically calls for spending cuts or tax increases that shift AD left. The economics of contraction are straightforward. The politics are nearly impossible. Elected officials who vote for tax hikes or slash popular programs tend to lose their seats. This is why genuine contractionary fiscal policy is vanishingly rare in practice, even when textbook models say it should happen.

The Spending Multiplier

When the federal government awarded a $42 million contract to rebuild the I-35W bridge in Minneapolis after its 2007 collapse, the money did not simply land in one company's bank account and sit there. The primary contractor, Flatiron-Manson, hired welders, crane operators, and engineers. Those workers deposited their paychecks and spent portions at grocery stores, restaurants, and car dealerships across the Twin Cities metro area. The grocery stores used that revenue to pay their own employees, who turned around and spent again. One injection of government dollars cycled through the economy over and over, each round slightly smaller than the last because some fraction of every dollar was saved rather than spent. Economists call this cascading effect the multiplier effect, and it explains why a single dollar of government spending can generate several dollars of total economic activity.

The size of the multiplier depends entirely on the marginal propensity to consume (MPC), the share of each additional dollar that households spend rather than save. The formula is clean: Spending multiplier = 1 / (1 - MPC). If the MPC is 0.8, meaning people spend 80 cents of every new dollar they receive, the multiplier equals 1 / 0.2 = 5. A $10 billion infrastructure bill would shift aggregate demand rightward by $50 billion as the initial spending cascades through successive rounds. Bump the MPC to 0.9 and the multiplier jumps to 10, because each dollar circulates through more hands before leaking out into savings. The higher the MPC, the longer the chain runs and the more powerful each government dollar becomes.

The Tax Multiplier

A question that surfaces on nearly every AP Macroeconomics exam in some form: why does a $10 billion tax cut produce a smaller shift in aggregate demand than $10 billion in direct government spending? The answer lies in what happens at the very first step. When the government spends $10 billion building highways, that entire sum enters the economy immediately. Someone gets paid. With a tax cut, the $10 billion lands in household bank accounts, but households do not spend every cent. If the MPC is 0.8, they save $2 billion right out of the gate. Only $8 billion actually enters the first round of the multiplier chain.

The formula captures this leakage: Tax multiplier = -MPC / (1 - MPC). The negative sign reflects the inverse relationship between taxes and aggregate demand. A tax cut increases AD while a tax hike decreases it. With an MPC of 0.8, the tax multiplier is -0.8 / 0.2 = -4. That $10 billion tax cut shifts AD right by $40 billion, compared to the $50 billion shift from equivalent direct spending.

The gap between the two multipliers is always exactly 1 in absolute value, regardless of the MPC. Spending multiplier minus tax multiplier always equals 1. This mathematical fact emerges from the initial-round leakage: government spending injects 100% of each dollar immediately while tax cuts lose the savings fraction before any spending occurs. That first-round difference of (1 - MPC) times the policy amount accounts for the entire gap.

Crowding Out

Deficit-financed stimulus carries a complication that the simple multiplier math ignores. When Congress spends more than it collects in taxes, the Treasury must sell bonds to cover the shortfall. Those bonds compete for the same pool of loanable funds that businesses want to tap for factory expansions, that developers need for housing projects, that consumers rely on for auto loans and mortgages. More borrowers chasing a finite supply of savings drives up interest rates across the economy.

Higher rates make capital investment more expensive. A manufacturing firm that would have built a new plant at 4% interest might shelve the project at 7%. A real estate developer cancels a condominium project. A family decides the monthly payment on a new car is no longer affordable. Private investment falls, partially offsetting the boost from government spending. This is the crowding-out effect, and it means the realized shift in aggregate demand is smaller than what the textbook multiplier predicts.

The severity of crowding out depends heavily on context. During the depths of the 2008 financial crisis, private investment demand had already collapsed. Interest rates sat near zero. There was very little private borrowing to displace, so government spending faced minimal crowding out. Contrast that with an economy at full employment where firms are actively competing for every available dollar of savings. In that environment, government borrowing can push rates up substantially and squeeze private investment hard. Full crowding out, where every government dollar displaces exactly one private dollar, represents the theoretical extreme. Partial crowding out is the norm in practice.

Automatic Stabilizers

Congress is slow. Passing a major spending bill requires committee hearings, floor debates, conference negotiations between the House and Senate, and a presidential signature. The American Recovery and Reinvestment Act of 2009 was considered fast by legislative standards, and it still took nearly two months from inauguration to signing. By the time relief money flows into the economy, the recession may have deepened or, in some cases, already ended. Automatic stabilizers bypass this political friction because they activate without any new legislation.

The U.S. has a progressive income tax system. When a worker loses her job or gets her hours cut, her taxable income drops and she falls into a lower bracket, owing less to the IRS automatically. Her disposable income does not collapse as steeply as her gross income did. During expansions, rising incomes push taxpayers into higher brackets, siphoning off purchasing power and acting as a natural brake on aggregate demand.

Unemployment insurance works the other side. When the economy contracts, more workers qualify for benefits without Congress lifting a finger. Unemployment claims surged from 211,000 per week in February 2020 to 6.9 million per week by late March. Those checks went overwhelmingly to people who would spend every dollar, cushioning the collapse in consumption. Safety net programs like SNAP follow similar logic, expanding enrollment automatically as incomes fall.

Automatic stabilizers dampen the business cycle's swings. They do not end deep recessions on their own. They are shock absorbers, not engines.

Budget Deficits and the National Debt

In fiscal year 2020, the federal government spent approximately $6.55 trillion and collected about $3.42 trillion in revenue. That $3.13 trillion gap was a budget deficit, the largest in U.S. history measured in raw dollars, though as a share of GDP the World War II deficits of 1943-1945 were proportionally larger. The Treasury covered the shortfall by selling bonds, notes, and bills to pension funds, foreign central banks, individual savers, commercial banks, and the Federal Reserve itself.

Stack every deficit the government has ever run, subtract the occasional surplus (1998 through 2001 being the most recent stretch), and you arrive at the national debt. A deficit is a flow: how much red ink accumulates in a single fiscal year. The debt is a stock: the total pile of outstanding IOUs at any given moment.

In theory, the budget should roughly balance over a full business cycle, running deficits during recessions to support demand and surpluses during booms to rebuild fiscal capacity. In practice, surpluses are extraordinarily rare because cutting spending and raising taxes is politically toxic regardless of the economic backdrop. Deficits have persisted even during the long expansion of 2010-2019.

Whether elevated debt poses a genuine economic threat remains one of the sharpest divides in the profession. Critics point to rising interest payments consuming an ever-larger share of the federal budget, the likelihood that future taxes must increase to service obligations, and the risk that creditors eventually demand higher yields. Defenders note that a sovereign government borrowing in its own currency can always make nominal payments, that the meaningful metric is debt-to-GDP ratio rather than the raw dollar figure, and that Japan has carried debt exceeding 250% of GDP for years while still borrowing at rock-bottom rates.

Fiscal Policy and the Phillips Curve

Every aggregate demand shift from fiscal policy has a mirror image on the Phillips Curve. When Congress runs expansionary fiscal policy by increasing government spending or cutting taxes, AD shifts right. Real GDP climbs, unemployment falls, and the price level rises. Translate that onto the short-run Phillips Curve: the economy slides up and to the left, trading lower unemployment for higher inflation.

Contractionary fiscal policy traces the opposite path. Spending cuts or tax increases shift AD left, cool the economy, and push the economy down and to the right along the short-run Phillips Curve. Unemployment rises. Inflation eases.

That trade-off holds in the short run. But there is a boundary. If the government keeps injecting stimulus after the economy has returned to full employment, workers and firms begin adjusting their inflation expectations upward. The short-run Phillips Curve itself shifts up. Unemployment eventually drifts back to the natural rate, but the economy arrives there with a permanently higher baseline of inflation. The long-run Phillips Curve captures this reality: a vertical line at the natural rate of unemployment, just as the LRAS curve is vertical at potential output. Fiscal policy can move the economy along the short-run curve but cannot hold unemployment below the natural rate indefinitely without accelerating inflation.

Connecting the graphs matters on the AP exam. An expansionary fiscal policy question should trigger three linked pictures in your mind: the AD/AS diagram (AD shifts right, output rises, price level rises), the money market (higher income raises money demand, pushing interest rates up), and the Phillips Curve (unemployment falls, inflation rises). Tracing those connections cleanly across all three models is where exam scores separate.

Worked Example

Congress is debating two proposals to fight a recession. The MPC is 0.75.

Option A: spend $20 billion on infrastructure. The spending multiplier is 1 / (1 - 0.75) = 1 / 0.25 = 4. The full $20 billion enters the economy on day one. Construction workers spend 75% of their income ($15 billion), the recipients of that spending do the same ($11.25 billion), and the chain continues until the rounds converge. Total AD shift: $20 billion x 4 = $80 billion.

Option B: cut taxes by $20 billion. The tax multiplier is -0.75 / 0.25 = -3. Households receive the $20 billion in relief but save 25% upfront, which is $5 billion. Only $15 billion enters the first spending round. The chain: $15 billion, then $11.25 billion, then $8.44 billion, and so on. Total AD shift: $20 billion x 3 = $60 billion.

Spending wins by $20 billion in total AD impact. On an AD/AS graph, both proposals shift AD to the right, but the spending option shifts it further. The multiplier gap is always exactly 1 (spending multiplier of 4 versus tax multiplier of 3) for any MPC value.

Both policies raise real GDP and the price level as the economy moves up along the SRAS curve. The practical policy question reduces to this: how much aggregate demand shift does Congress want per dollar of fiscal commitment?