Finance📅 12 March 2025⏱ 5 min read
Effective Tax Rate vs Marginal Tax Rate: What You Actually Pay
Hearing you are in the 40% tax bracket makes it sound like you pay 40% on everything. You don't. Here is the difference between marginal and effective rates, and how to calculate your true tax burden.
JW
James WhitfieldPersonal Finance & Maths WriterJames has written about personal finance, health metrics, and everyday mathematics for over six years. He holds a BSc in Mathematics from the University of Leeds.
The marginal tax rate is the rate on your last pound of income. The effective tax rate is your actual average — almost always much lower. Confusing the two leads people to make poor financial decisions.
The UK Tax Bands (2024/25)
Personal Allowance: £0 - £12,570 → 0% tax
Basic Rate: £12,571 - £50,270 → 20% tax
Higher Rate: £50,271 - £125,140 → 40% tax
Additional Rate: above £125,140 → 45% tax
Each band applies only to the income within that band —
not to total income.
A person earning £60,000 does NOT pay 40% on £60,000.
They pay:
0% on first £12,570 = £0
20% on £12,571-£50,270 (£37,700) = £7,540
40% on £50,271-£60,000 (£9,730) = £3,892
Total income tax: £11,432
Calculating Effective Tax Rate
Effective Tax Rate = Total Tax Paid / Gross Income x 100
At £60,000 income:
Total tax: £11,432
Effective rate: £11,432 / £60,000 x 100 = 19.05%
At £80,000 income:
0% on £12,570 = £0
20% on £37,700 = £7,540
40% on £29,730 = £11,892
Total: £19,432
Effective rate: £19,432 / £80,000 = 24.29%
At £120,000 income (personal allowance tapered):
Personal allowance reduces by £1 for every £2 above £100,000
At £120,000: PA = £12,570 - £10,000 = £2,570
Total tax (approx): £42,700
Effective rate: £42,700 / £120,000 = 35.6%
The 60% Trap: £100k-£125k
Income between £100,000 and £125,140 has an effective 60% marginal rate:
For every £2 earned above £100,000:
- £1 is lost from the personal allowance
- That £1 (now taxable at 40%) = £0.40 tax
- Plus 40% on the actual £2 earned = £0.80 tax
- Total tax on £2 extra: £1.20 → 60% rate
Strategies to escape the 60% trap:
Make pension contributions to bring income below £100,000
(Pension contributions reduce adjusted net income)
Example: £110,000 salary, make £10,000 pension contribution
Adjusted net income: £100,000 — personal allowance restored
Tax saving: ~£6,000 compared to not contributing
This is far more valuable than the standard 40% relief would suggest.
Including National Insurance in True Tax Burden
Income tax alone understates the tax burden on employment income.
NI adds significant cost:
Employee NI 2024/25:
£12,570-£50,270: 8%
Above £50,270: 2%
At £60,000 income:
Income tax: £11,432
Employee NI: (£37,700 x 8%) + (£9,730 x 2%) = £3,016 + £195 = £3,211
Total employee deductions: £14,643
True effective rate: £14,643 / £60,000 = 24.4%
Add employer NI (13.8% on earnings above £9,100):
Employer NI: (£60,000 - £9,100) x 13.8% = £7,024
True all-in cost to employer: £60,000 + £7,024 = £67,024
Employee receives: £45,357
All-in effective rate: (£67,024 - £45,357) / £67,024 = 32.3%