In simple terms
A friendly intro before the formal notes — no formulas yet.
Fair Shares, Not Equal Shares
Markets reward people very unequally. Economists measure how unequal a country is, ask whether that is fair, and study the tools — mainly taxes and benefits — a government can use to close the gap without doing so much damage to incentives that the whole economy suffers.
Picture a country's yearly income as a single cake. If everyone got an identical slice that would be perfect EQUALITY. But some people worked night shifts, some took huge risks starting firms, some inherited a bakery — so a fair (EQUITABLE) cut is not the same as an identical cut. The Lorenz curve draws exactly how lopsided the slicing is; the Gini coefficient turns that picture into one number; and taxes and benefits are how the government trims the biggest slices to top up the smallest — mindful that if it trims too hard, fewer people will bother baking.
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Separate the two ideas: equality means identical shares; equity means fair shares — they are not the same thing.
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Measure the current distribution with the Lorenz curve, then summarise it in one number, the Gini coefficient (0 = perfect equality, 1 = perfect inequality).
- 3
Diagnose poverty (absolute vs relative), its causes, and the self-reinforcing poverty cycle.
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Apply the tools — progressive taxes and transfer payments pull the Lorenz curve towards the 45° line — while weighing the equity–efficiency trade-off.
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Key formulas
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Full topic notes
Formal explanation with the rigour you need for the exam.
Equity is not the same as equality
Students lose marks every year by treating these words as synonyms. EQUALITY means sameness: an equal distribution gives everyone identical shares. EQUITY means fairness, and fairness usually requires treating different people differently — more help for those with greater need, or reward in proportion to effort and contribution. A society that pays a surgeon more than a trainee is unequal, yet most people would call it equitable. A benefit that is larger for a disabled claimant than a healthy one is unequal but widely seen as fair. So a policy can raise equity without raising equality, and forcing perfect equality can even feel inequitable.
Equality = identical outcomes (or identical opportunities). It is a factual, measurable idea.
Equity = fairness. It is a NORMATIVE (value-based) idea, so people reasonably disagree about it.
Horizontal equity = treating people in the same situation the same way. Vertical equity = treating people in different situations differently (e.g. taxing higher earners at higher rates).
The goal of redistribution policy is usually greater EQUITY and less poverty — not perfect equality.
Measuring inequality: the Lorenz curve
To compare countries or track a country over time we need to measure the distribution of income. The Lorenz curve is the standard picture. Rank the whole population from poorest to richest and plot, on the horizontal axis, the cumulative percentage of the population and, on the vertical axis, the cumulative percentage of total income they receive. The 45° diagonal is the LINE OF PERFECT EQUALITY: on it the poorest 20% of people earn exactly 20% of income, the poorest 60% earn 60%, and so on. The actual Lorenz curve always lies below this line and bows away from it — the poorest 20% might earn only 5% of income. The more the curve sags towards the bottom-right corner, the more unequal the distribution.
The Lorenz curve is powerful because it lets you compare distributions visually and show the effect of policy: draw the pre-tax-and-transfer curve, then the post-tax-and-transfer curve nearer the 45° line, and you have illustrated redistribution in one diagram.
X-axis: cumulative % of population, ranked poorest to richest.
Y-axis: cumulative % of total income.
Line of perfect equality: the 45° line where each population share earns an identical income share.
Area A (between the 45° line and the curve) captures the amount of inequality; Area B is the area beneath the curve.
A curve that shifts TOWARDS the 45° line means LESS inequality; a curve that bows further away means MORE inequality.
Turning the picture into a number: the Gini coefficient
A curve is hard to rank in a league table, so we summarise it in one number: the Gini coefficient. It measures how much of the area beneath the 45° line falls in the 'inequality gap' (Area A). It runs from 0 (the curve sits on the 45° line — perfect equality) to 1 (the curve hugs the axes — one person has all the income). Most countries lie between about 0.25 and 0.65. A higher Gini means more inequality; a fall in the Gini over time means the distribution has become more equal.
Gini coefficient =
Area A = the region between the line of perfect equality and the Lorenz curve. Area B = the region beneath the Lorenz curve. Because (Area A + Area B) is the whole triangle under the 45° line, the Gini is simply the fraction of that triangle taken up by the inequality gap.
The Gini coefficient and the Lorenz curve are two views of the SAME information. The Gini rises when the Lorenz curve bows further from the 45° line, and falls when it moves towards it. In an evaluation, use both together: cite the Gini for precision and describe the Lorenz-curve shift for the mechanism. Never claim a country is 'more equal' because its Gini is HIGHER — that is backwards, and it is one of the most common errors examiners see.
Poverty: absolute, relative, and the cycle
Inequality is about the SHAPE of the distribution; poverty is about the BOTTOM of it. Economists distinguish two kinds. ABSOLUTE poverty is an inability to afford the basic necessities of life — food, clean water, shelter, basic health care — measured against a fixed subsistence line (such as the international extreme-poverty line). RELATIVE poverty is being far worse off than the typical person in your own society, usually defined as living below a set fraction (commonly 60%) of median income. A wealthy country may have almost no absolute poverty yet substantial relative poverty; as a country grows richer, absolute poverty tends to fall but relative poverty can persist because the median rises too.
Causes of poverty: low or no wages (unemployment, low-skill or insecure work), lack of human capital (poor education/health), discrimination, geography, disability or age, and inherited disadvantage.
The poverty cycle (trap): low income → low or zero saving → little spending on education, health and capital → low productivity → low income again. The loop repeats within a lifetime and across generations.
Because the cycle is self-reinforcing, markets alone rarely break it — this is a key justification for government INTERVENTION targeted at the poorest.
Consequences of poverty and high inequality: lower economic well-being, poorer health and education outcomes, reduced social mobility, and possible social and political instability.
The tax system: direct vs indirect, and how the burden falls
Taxes are classified in two independent ways. First, by WHAT they are levied on. DIRECT taxes fall on income or wealth and are paid straight to the government by the person or firm who bears them — income tax, corporation tax, capital-gains and wealth taxes. INDIRECT taxes fall on spending and are collected through a third party, the seller, who passes them to the government — VAT/GST and excise duties on fuel, alcohol and tobacco. Second, and separately, by HOW the burden changes with income — measured by the AVERAGE tax rate (tax paid ÷ income).
Progressive tax: average tax rate RISES with income — higher earners pay a larger share of income. This is the tax structure that reduces inequality and pulls the Lorenz curve towards the 45° line. Typical example: income tax with rising marginal bands.
Proportional (flat) tax: average tax rate is CONSTANT — the same percentage at every income. On its own it leaves relative shares, and so the Gini, unchanged.
Regressive tax: average tax rate FALLS as income rises — the poor pay a larger share of their income. Indirect taxes such as VAT are regressive in effect. This structure WIDENS inequality.
Direct/indirect and progressive/regressive are separate axes: income tax is direct and (usually) progressive; VAT is indirect and regressive.
You must be able to explain WHY a flat-rate indirect tax like VAT is regressive — the marker is testing whether you reason in PROPORTIONS. Suppose a £120 item carries £20 of VAT. For someone earning £200 a week that £20 is 10% of income; for someone earning £2,000 a week it is 1%. The cash is identical, but the poorer person surrenders a far larger PROPORTION of income, because lower-income households spend a bigger share of what they earn (and save less). Always argue from proportion of income, never absolute amount.
Transfer payments and other redistribution policies
Taxation is only one side of redistribution — it determines what is taken. What is given back matters just as much. TRANSFER PAYMENTS are government payments to individuals for which no good or service is provided in return: unemployment benefits, state pensions, child benefit, disability and housing support. They raise the disposable incomes of the poorest directly, so the post-transfer Lorenz curve moves towards the 45° line. Governments combine transfers with other tools.
Transfer payments — cash benefits (pensions, unemployment and disability benefit, child support) that top up low incomes directly.
Government-provided goods and services — 'in-kind' benefits such as state education and health care, which raise real living standards and, over time, human capital, helping to break the poverty cycle.
Minimum wages and labour-market policy — raise the incomes of the low-paid (though with possible employment effects covered elsewhere).
Investment in human capital and infrastructure — education, training and health spending targeted at the poor tackle the ROOT CAUSES of low income rather than only its symptoms.
A credible redistribution strategy usually blends progressive taxes (to fund it) with transfers AND longer-term investment in opportunity.
The equity–efficiency trade-off
Redistribution is not free. Taking income from high earners and topping up low earners can improve equity and reduce poverty, but it can also blunt incentives: high marginal tax rates may discourage extra work, saving, investment and entrepreneurial risk, while generous benefits can, if poorly designed, weaken the incentive to seek work (the 'benefits trap'). If these effects shrink total output, the economy has a smaller pie to share — the classic EQUITY–EFFICIENCY TRADE-OFF. The size of the trade-off is debated and empirical: moderate redistribution that funds education and health can even RAISE efficiency by making the workforce more productive and by reducing the waste of talent trapped in poverty. The policy craft lies in choosing tools that buy the most equity for the least loss of efficiency.
The case for redistribution: reduces poverty and relative deprivation, improves overall economic well-being, can raise long-run productivity via health and education, and supports social and political stability.
The case against (or for caution): disincentive effects on work, saving and investment; tax avoidance, evasion and capital/labour flight; administrative cost; and the risk of dependency if benefits are badly designed.
Judgement: the question is rarely 'redistribute or not' but 'how, how much, and with which mix of tools' — balancing equity gains against efficiency costs.
Common mistakes examiners penalise
Treating equity and equality as the same word — equality is sameness (measurable); equity is fairness (normative). A fair policy is often deliberately unequal. Muddling them is an instant marker for a weak answer.
Defining progressive/regressive by the amount of cash paid — the rich pay more money under almost every tax. Progressivity is about the PROPORTION of income (the average tax rate), so always argue from percentages, not totals.
Reading the Gini backwards — a HIGHER Gini means MORE inequality, and a fall in the Gini means the distribution has become more equal. Never say a rising Gini shows a fairer society.
Claiming a Gini of 0 is the goal — perfect equality destroys incentives; policy targets equity and lower poverty, not zero inequality.
Confusing absolute with relative poverty — absolute poverty is a fixed subsistence line; relative poverty is measured against the society's median. Growth can cut absolute poverty while relative poverty persists.
One-sided evaluation — asserting progressive tax 'reduces inequality' with no mention of disincentives, avoidance/evasion, whether it treats root causes, or the need for complementary policies. Part (b) marks REQUIRE both sides and a reasoned judgement.
A diagram drawn but not explained — an unlabelled or unexplained Lorenz-curve/tax diagram cannot reach the top band. Reference the axes and the shift in words.
Key concepts in this lesson
This lesson develops three of the course's key concepts. Equity — the fairness of the income distribution, distinct from mere equality — frames the whole topic. Intervention — government use of taxes, transfers and public services to reshape market outcomes — is the toolkit. And economic well-being — living standards and the reduction of poverty — is the ultimate objective against which redistribution is judged. Keep all three in view: a strong part (b) answer links the mechanics of a policy back to its effect on equity and well-being, while weighing the efficiency cost of intervention.
Worked examples
See the formulas applied — reveal one step at a time, like the exam.
Reading a Lorenz curve. The table gives the income distribution of the country of Meridia.
| Cumulative % of population (poorest first) | Cumulative % of income |
|---|---|
| 0 | 0 |
| --- | --- |
| 20 | 5 |
| 40 | 14 |
| 60 | 28 |
| 80 | 50 |
| 100 | 100 |
(a) On the line of perfect equality, what share of income would the poorest 40% receive? [1] (b) What share do the poorest 40% ACTUALLY receive in Meridia, and what does the gap tell you? [2] (c) The richest 20% of the population — what share of total income do they take? Show your working. [2]
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(a) On the 45° line of perfect equality every population share earns an identical income share, so the poorest 40% of people would receive 40% of income. [1]
A progressive-tax calculation. Highland uses a two-band income tax:
- 0% on income up to
- 25% on every dollar of income above
Person A earns $30,000. Person B earns $90,000. (a) Calculate the total tax paid and the average tax rate (ATR) for each person. [4] (b) Use your ATRs to prove the tax is progressive. [1] (c) Explain, using the idea of the Lorenz curve, how this tax affects income inequality. [3]
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**(a) Person A (income
- Taxable income above the threshold: 15,000 =
- Total tax: 0.25 × 3,750**
- ATR: (30,000) × 100 = 12.5%
Paper 1, part (b): Evaluate the effectiveness of progressive taxation as a policy to reduce income inequality. [15 marks]
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Model answer:
How it all connects
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Glossary
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Equality vs equity
Equality = everyone gets the SAME (identical outcomes or opportunities). Equity = FAIRNESS, which usually means treating people according to need or contribution and can justify UNEQUAL outcomes. A society can be more equitable without being more equal — and vice versa.
Key takeaways
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- ✓
Equality = identical outcomes (or identical opportunities). It is a factual, measurable idea.
- ✓
Equity = fairness. It is a NORMATIVE (value-based) idea, so people reasonably disagree about it.
- ✓
Horizontal equity = treating people in the same situation the same way. Vertical equity = treating people in different situations differently (e.g. taxing higher earners at higher rates).
- ✓
The goal of redistribution policy is usually greater EQUITY and less poverty — not perfect equality.
Practice — then mark it
The whole point: a real Cambridge question, marked mark-by-mark.
Get a Paper 1 (b) evaluation marked: is progressive taxation an effective way to reduce income inequality?
Get a Paper 1 (b) evaluation marked: is progressive taxation an effective way to reduce income inequality?
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Checkpoint
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Before you move on: do Get a Paper 1 (b) evaluation marked: is progressive taxation an effective way to reduce income inequality? on paper, snap a photo, and get examiner-style feedback on exactly where you win and lose marks.