Public finance and taxation

Understand how governments raise, spend, and borrow money, and how those choices affect people and the wider economy.

No prior knowledge of public finance is needed. New terms are bold, explained on first use, and linked to the glossary, which links back to their explanations here.

The amounts and rates below are invented teaching examples. Unless stated otherwise, they are in dollars, cover one budget year, and ignore borrowing interest, inflation, administrative costs, and behavioral changes. Tax rules and public programs vary by jurisdiction and change over time.

What public finance covers

Public finance is the study of how public authorities raise money, use it to provide services or make transfers, and borrow when spending and revenue do not match. It asks both practical questions, such as whether a budget can pay its bills, and policy questions, such as who pays and who benefits.

Governments are not households. A government may collect taxes across many years, provide services to millions of people, and have legal authority to borrow or change taxes. Still, a simple household analogy can help: revenue is money coming in, expenditure is money going out, and borrowing creates an obligation for future budgets.

Fiscal policy means government decisions about spending and taxation used to influence economic activity. It is different from monetary policy, which is carried out by a central bank. A government can use fiscal policy to provide services, support incomes, respond to a downturn, or reduce demand when the economy is overheating. Each choice has tradeoffs and distributional effects.

Read a public budget

A public budget is a plan for public revenue and expenditure over a stated period. Public revenue includes money received by a government, such as taxes, fees, fines, and some income from public assets. Public expenditure is money the government spends on services, infrastructure, transfers, wages, interest, and other obligations.

Imagine a city has this one-year plan:

Category	Amount
Tax revenue	$72 million
Fees and other revenue	$8 million
Public services	$50 million
Infrastructure	$12 million
Transfers and benefits	$10 million
Other spending	$5 million

Total revenue is $72 million + $8 million = $80 million. Total expenditure is $50 million + $12 million + $10 million + $5 million = $77 million. The planned balance is $80 million − $77 million = a $3 million surplus.

A surplus does not automatically mean taxes are too high or services are underfunded. The city may be saving for a large project, repaying debt, or building a reserve. A deficit may likewise be deliberate if borrowing pays for a long-lived bridge, but it creates future obligations that the budget must account for.

The International Monetary Fund’s overview of fiscal policy provides broader context on government revenue, spending, and borrowing.

Compare common taxes

A tax is a compulsory payment to a public authority, usually used to fund public purposes. A tax base is the income, spending, property value, transaction, or other measure to which a tax rate applies.

Common categories include:

Tax type	Typical base	Simple example
Income tax	Earnings or other income	A percentage of taxable wages
Consumption tax	Purchases of goods or services	A sales tax added at checkout
Property tax	Assessed property value	A yearly charge on a home or land
Capital gains tax	Increase in an asset’s value when sold	Tax on a realized investment gain

A progressive tax takes a larger percentage as the tax base increases. For example, a system might charge 5% on the first $20,000 of taxable income and 15% on the next $20,000. Someone with $40,000 would pay $1,000 + $3,000 = $4,000, an average rate of 10%. The 15% rate applies only to the second band, not to all $40,000.

A consumption tax is charged when people buy goods or services. If a purchase costs $80 before a 5% tax, the tax is $80 × 0.05 = $4, and the total is $84. The effect on different households depends on what they buy and how much of their income they spend. A tax’s legal payer, the person or business required to send it to the authority, may differ from the person who bears its economic cost through prices or wages.

Understand public services

Governments spend money on services such as courts, roads, schools, health programs, emergency response, and administration. A public good is a service or benefit that can be difficult to restrict to paying users and where one person’s use may not substantially reduce what is available to others. National defense is a common example, although real services do not always fit neatly into one category.

Public spending can also address external effects, provide support during hardship, or make services available more widely. These goals do not prove that a particular program is effective. Evaluation should ask what the program costs, who benefits, what alternatives exist, and what unintended effects may occur.

Connect deficits and debt

When expenditure is higher than revenue in a budget period, the difference is a budget deficit. If the city above instead spent $86 million, its deficit would be $86 million − $80 million = $6 million. It could cover that gap by using reserves, raising revenue, reducing spending, or borrowing.

Public debt is the accumulated amount a public authority owes to lenders. A new deficit can add to debt, while a surplus can be used to repay it. Debt is not the same as the deficit: the deficit is a period’s shortfall, while debt is a stock measured at a point in time.

Suppose a city begins with $40 million of debt, borrows $6 million to cover the year’s deficit, and repays $2 million of older debt. Ignoring interest, ending debt is $40 million + $6 million − $2 million = $44 million. Interest payments would be additional expenditure in later budgets. Whether debt is manageable depends on its interest cost, maturity, currency, revenue capacity, economic conditions, and the purpose of borrowing.

A pension is income paid after a person retires or meets another qualifying condition. A social insurance program collects contributions or taxes to provide defined support when people face risks such as old age, disability, unemployment, or illness.

Programs differ. In a funded arrangement, contributions are invested to help pay future benefits. In a pay-as-you-go arrangement, current contributions and other revenue help pay current benefits. A program can also combine these features. Its long-term position depends on eligibility, benefit rules, contribution rates, investment results, population age, employment, and policy changes. A promise of future benefits is not the same as money already held in a personal account.

Check your understanding

Try these before reading the answers:

A government receives $120 million and spends $135 million in one year. Is the result a surplus or deficit, and how large is it?
A 6% consumption tax applies to a $250 purchase. What is the tax and total price?
A country starts with $500 million of public debt, borrows $30 million, and repays $18 million, excluding interest. What is its ending debt?
Why is a budget deficit not the same thing as public debt?

Answers

A $15 million deficit. Spending exceeds revenue by $135 million − $120 million.
$15 tax and $265 total. The tax is $250 × 0.06 = $15; add it to the pre-tax price.
$512 million. $500 million + $30 million − $18 million = $512 million.
A deficit is a shortfall during a period; debt is the accumulated amount owed at a point in time. A deficit can increase debt, but repayment, refinancing, asset sales, and other transactions can also change debt.

Terms introduced in this lesson

Use these links to revisit definitions. Each glossary entry links back to its explanation above.

Keep learning

Future lessons can examine government budget processes, tax incidence and tax design, sovereign and municipal debt in more detail, public pensions, and social insurance sustainability. For economic context, continue with Economics and the financial system. For household-level applications, see Personal finance and financial wellbeing.