Taxation (The Role of the State in the Macroeconomy)

A tax is a compulsory payment to the government, used to fund public spending and to influence the economy. Taxes divide into two families depending on what is taxed.

Direct taxes are levied on income or wealth, and the person or firm on whom the tax is levied pays it directly to the government. The main examples are:

• Income tax — a tax on individuals' earnings;
• Corporation tax — a tax on companies' profits;
• National Insurance Contributions (NICs) — a tax on wages that funds social security.

Indirect taxes are levied on spending on goods and services. They are collected by the seller and passed on to the buyer in a higher price, so the incidence is indirect. The main examples are:

• VAT (Value Added Tax) — an ad valorem tax (a percentage of price);
• Excise duties — specific taxes (a fixed amount per unit) on fuel, alcohol and tobacco.

Feature	Direct tax	Indirect tax
Tax base	Income or wealth	Spending on goods/services
Examples	Income tax, corporation tax, NICs	VAT, fuel/alcohol/tobacco duties
Who pays the government	The person/firm taxed	The seller, who passes it on
Ease of collection	Harder, needs assessment	Easier — collected at point of sale
Distribution effect	Usually progressive (can redistribute)	Often regressive

A key link forward: whether a tax is direct or indirect is a separate question from whether it is progressive, proportional or regressive — that second question is about how the tax burden changes with income, which the next section defines precisely.

The single most important idea in this subtopic is that a tax is classified by what happens to the AVERAGE tax rate as income rises — not by whether the amount paid rises. The average tax rate is the proportion of income paid in tax:

$\text{Average tax rate} = \frac{\text{tax paid}}{\text{income}} \times 100$

• A progressive tax takes a rising share of income as income rises — the average tax rate increases with income. The rich pay a larger proportion, not just a larger amount. (UK income tax, with rising tax bands, is the classic example.)
• A proportional (flat) tax takes the same share of income at every level — the average tax rate is constant (e.g. a flat 20% on all income).
• A regressive tax takes a falling share of income as income rises — the average tax rate decreases as income rises. A poorer person pays a larger proportion of their income than a richer person.

System	Average tax rate as income rises	Who pays the larger share
Progressive	Rises	Higher-income earners
Proportional / flat	Constant	Everyone the same share
Regressive	Falls	Lower-income earners

Why indirect taxes tend to be regressive. Suppose a £1 duty is added to a good bought by everyone. A person earning £10,000 who spends £100 on the good pays the same £1 as a person earning £100,000. But £1 is a larger fraction of the low income than the high income, so the average rate (tax ÷ income) is higher for the poorer person — a regressive outcome. This is why heavy reliance on VAT and excise duties raises equity concerns.

Watch the wording. A regressive tax can still take a larger absolute amount from a rich person while taking a larger proportion from a poor person — always test the share of income, i.e. the average rate.

Two rates measure how heavily income is taxed, and Unit 4 expects you to calculate both.

Average tax rate (ATR) — the overall share of income paid in tax:

$\text{Average tax rate} = \frac{\text{tax paid}}{\text{income}} \times 100$

Marginal tax rate (MTR) — the tax rate on the next (extra) pound of income earned:

$\text{Marginal tax rate} = \frac{\Delta \text{tax}}{\Delta \text{income}} \times 100 = \frac{\text{change in tax paid}}{\text{change in income}} \times 100$

Worked illustration. Suppose the first £12,000 of income is tax-free, income from £12,000 to £50,000 is taxed at 20%, and income above £50,000 at 40%. A person earning £60,000 pays:

• £0 on the first £12,000;
• 20% × (£50,000 − £12,000) = 20% × £38,000 = £7,600;
• 40% × (£60,000 − £50,000) = 40% × £10,000 = £4,000;
• total tax = £7,600 + £4,000 = £11,600.

Their average tax rate = £11,600 ÷ £60,000 × 100 = 19.3%. Their marginal tax rate = 40% (the rate on the next pound earned, since they are in the top band). Notice the marginal rate (40%) is well above the average rate (19.3%) — the signature of a progressive system.

Why the distinction matters. Incentives are driven by the marginal rate: it is the tax on extra effort — overtime, promotion, an extra investment — so a high MTR is what can discourage work and enterprise. The average rate measures the overall burden and how the tax is shared. Confusing the two is a classic error.

The purposes of taxation. Governments tax for several overlapping reasons:

• To fund public spending — the primary purpose: paying for healthcare, education, defence, infrastructure and welfare.
• To redistribute income — progressive taxes take proportionately more from the rich; the revenue funds benefits and services that help the less well-off, reducing inequality.
• To correct market failure — taxing goods with negative externalities (pollution, congestion) or demerit goods (tobacco, alcohol, sugar) internalises the external cost and cuts over-consumption.
• To manage aggregate demand (AD) — as a tool of fiscal policy, cutting taxes raises disposable income and boosts AD; raising taxes cools an overheating economy and helps control inflation.
• To discourage particular activities — e.g. tariffs to protect domestic industry, or high duties to reduce harmful consumption.

Adam Smith's canons of taxation. In The Wealth of Nations (1776), Adam Smith set out four principles of a good tax, and modern economists add two more:

Canon	A good tax should be…
Equity (equality)	Fair — related to ability to pay (those who can afford more should pay more).
Certainty	Clear and predictable — taxpayers should know what, when and how much to pay.
Convenience	Easy to pay — collected in a way and at a time convenient to the payer (e.g. PAYE deducted from wages).
Economy	Cheap to collect — the cost of collection should be small relative to the revenue raised.
Efficiency (modern)	Should not distort economic behaviour or incentives more than necessary.
Flexibility (modern)	Should be easy to change to suit economic conditions (e.g. adjust as part of fiscal policy).

These canons give you a ready-made evaluation framework: to judge any tax, ask whether it is equitable, certain, convenient, economical, efficient and flexible. A tax rarely scores well on all six, so trade-offs — especially equity vs efficiency — are where the marks lie.

The Laffer curve shows the relationship between the tax rate and total tax revenue. It is a cornerstone of supply-side economics and a standard Unit 4 diagram.

The logic starts from two endpoints:

• At a 0% tax rate, the government raises no revenue — nothing is taxed.
• At a 100% tax rate, the government also raises no revenue — no one has any incentive to earn income they cannot keep, so the tax base collapses (people stop working, or move all activity into the untaxed black market).

Between these extremes, revenue first rises as the rate increases, reaches a maximum at the revenue-maximising rate t*, and then falls. Beyond t*, each further rise in the tax rate does more harm to the tax base than good to the rate, so revenue drops.

Reading the diagram:

• The curve starts at the origin (0 revenue at a 0% tax rate) and returns to zero revenue at a 100% tax rate.
• It rises to a maximum revenue Rmax at the revenue-maximising rate t*, marked with a dropline to the axis; the marked peak sits on the curve.
• Left of t* (revenue rising): the rate is below the peak, so raising it increases revenue.
• Right of t* (revenue falling): the rate is above the peak, so cutting it could actually raise revenue.

Why revenue falls beyond t*. Very high tax rates shrink the tax base through:

• Disincentives — high marginal rates make extra work, saving and investment less worthwhile, so people work and earn less.
• Tax avoidance — legal schemes to reduce tax liability multiply as rates rise.
• Tax evasion — illegal non-payment and the black/informal economy grow.
• Emigration ('brain drain') — high earners and firms relocate to lower-tax countries, and inward investment falls.

The policy claim. Supply-side economists use the Laffer curve to argue that if an economy is to the right of t*, a tax cut can increase revenue by expanding the tax base. The catch — and the key evaluation point — is that no one knows exactly where t* is, and it differs by tax, country and time. A tax cut only raises revenue if the economy is genuinely beyond the peak.

Taxation does far more than raise money — it changes behaviour and the shape of the income distribution. Three effects matter most for Unit 4.

1. Effects on incentives. Because incentives depend on the marginal tax rate:

• High marginal income-tax rates can reduce the incentive to work extra hours, seek promotion or enter the labour force — a disincentive effect. (Though some may work more to maintain their target income — the income effect — so the net effect is ambiguous.)
• High corporation tax can reduce the incentive to invest and the funds available for it, lowering the capital stock and future growth.
• High taxes on saving (or on interest) can discourage saving. These are the disincentives behind the falling section of the Laffer curve and the supply-side case for lower marginal rates.

2. Effects on output. By blunting incentives to work, invest and take risks, high taxes can lower productive potential and shift long-run aggregate supply (LRAS) leftward over time; supply-side economists argue lower marginal rates raise output and employment. Working in the opposite direction, tax revenue funds public goods, infrastructure, education and health that raise productivity — so the output effect of tax depends on how the revenue is spent, not just on the rates.

3. Effects on the distribution of income. This is the redistribution channel:

• A progressive tax system takes a larger share from high earners, and the revenue funds benefits and public services that help lower-income households — narrowing the gap between rich and poor.
• A regressive system (heavy reliance on VAT and excise duties) does the opposite, taking a larger share from the poor and widening inequality.
• Measured on a Lorenz curve, a more progressive tax-and-benefit system pulls the curve closer to the line of equality (a lower Gini coefficient).

The core trade-off: equity vs efficiency. Making the system more progressive improves equity (fairer distribution) but can worsen efficiency (higher marginal rates blunt incentives and, beyond t* on the Laffer curve, even reduce revenue). Every judgement about tax policy is ultimately a judgement about where to strike this balance — the reason 'evaluate' questions on tax reward candidates who weigh fairness against incentives rather than asserting one side.