When you earn a wage or salary, you do not keep all of it — the government deducts income tax and National Insurance before you receive your take-home pay. At GCSE you need to calculate gross pay, apply tax bands, work out National Insurance, and find net pay.
What is the difference between gross pay and net pay?
Gross pay is your total earnings before any deductions. It includes your basic salary or wages, plus overtime, bonuses, or commission if applicable.
Net pay (sometimes called take-home pay) is what you actually receive after all deductions:
Net pay = Gross pay − Income tax − National Insurance contributions (and any other deductions)
Your payslip shows both figures each month.
How does income tax work in the UK?
Income tax is charged on income above a tax-free threshold called the personal allowance. You do not pay income tax on income up to the personal allowance; above it, different rates apply in bands.
GCSE questions almost always supply the tax bands in the question. A typical set of bands looks like this:
| Band | Taxable income | Rate |
|---|---|---|
| Personal allowance | Up to £12,570 | 0% |
| Basic rate | £12,571 to £50,270 | 20% |
| Higher rate | £50,271 to £125,140 | 40% |
Important: you pay each rate only on the income within that band, not on your total income.
Worked example: calculating income tax
Marcus earns £34,000 per year. Use the tax bands in the table above to calculate his annual income tax.
Step 1: Subtract the personal allowance. Taxable income = £34,000 − £12,570 = £21,430
Step 2: All of Marcus's taxable income falls within the basic rate band (up to £50,270), so: Income tax = 20% × £21,430 = 0.20 × £21,430 = £4,286
Step 3 (check): His taxable income (£21,430) is less than the top of the basic rate band (£37,700 above the allowance), so no higher rate applies. ✓
Now suppose Marcus earns £60,000 instead.
- Taxable income = £60,000 − £12,570 = £47,430
- Basic rate on first £37,700: 20% × £37,700 = £7,540
- Higher rate on remainder: 40% × (£47,430 − £37,700) = 40% × £9,730 = £3,892
- Total income tax = £7,540 + £3,892 = £11,432
How does National Insurance work?
National Insurance (NI) is a separate deduction, also charged in bands. A typical exam question might give:
| Band | Earnings | Employee NI rate |
|---|---|---|
| Below lower earnings limit | Up to £12,570 | 0% |
| Standard rate | £12,571 to £50,270 | 8% |
| Above upper earnings limit | Above £50,270 | 2% |
Worked example: Marcus earns £34,000. Calculate his annual NI contribution.
NI = 8% × (£34,000 − £12,570) = 0.08 × £21,430 = £1,714.40
How do you calculate net pay?
Once you have income tax and NI, subtract both from gross pay.
Continued example (Marcus, £34,000):
| Amount | |
|---|---|
| Gross pay | £34,000.00 |
| Income tax | −£4,286.00 |
| National Insurance | −£1,714.40 |
| Net pay (annual) | £28,000 − £0.40 = £27,999.60 |
Wait — let me redo: £34,000 − £4,286 − £1,714.40 = £27,999.60
Monthly net pay = £27,999.60 ÷ 12 = £2,333.30 (to the nearest penny)
What other personal finance topics appear at GCSE?
Beyond income tax and NI, GCSE personal finance questions can include:
- Overtime: standard rate for the first n hours per week, then time-and-a-half or double time for extra hours
- Commission: a percentage of sales added to a base wage
- Piecework: paid a fixed amount per item produced
- Budgeting: given income and a list of expenses, find the surplus or shortfall
Overtime example: Priya earns £14 per hour for a 35-hour week. She works 42 hours one week and is paid time-and-a-half for overtime.
- Basic pay: 35 × £14 = £490
- Overtime hours: 42 − 35 = 7
- Overtime rate: 1.5 × £14 = £21 per hour
- Overtime pay: 7 × £21 = £147
- Gross pay = £490 + £147 = £637
Frequently asked questions
Do GCSE questions give me the tax bands, or do I have to memorise them?
GCSE questions always supply the tax rates and bands in the question. You do not need to memorise specific UK tax rates. However, you do need to understand the structure: that the personal allowance is tax-free, and that you pay each rate only on the portion of income within that band.
Why do I pay tax on only part of my income?
The personal allowance is a tax-free threshold — income up to that amount is not taxed at all. The remaining income is called taxable income, and it is this amount that you split across the tax bands. This system is called a progressive tax because higher earners pay a higher proportion of their income in tax.
What is the difference between an income tax rate and an effective tax rate?
The rate on each band (20%, 40%) is the marginal rate — the rate paid on the next pound of income. The effective rate (or average rate) is total tax ÷ gross income × 100, which is always lower than the highest marginal rate you hit. Exam questions that ask "what percentage of his income does Marcus pay in tax?" are asking for the effective rate.
What if a question asks for weekly or monthly figures?
GCSE questions may give annual, monthly, or weekly figures. Convert everything to the same time period before calculating. Common conversions: annual ÷ 12 = monthly; annual ÷ 52 = weekly; weekly × 52 = annual.
Practise income tax and financial maths questions with step-by-step guidance from Professor Pi at aitutors.me.