Taking on extra work raises an obvious question: how much tax on a second job will you actually pay? Usually 20% from the first pound, because your £12,570 personal allowance is normally used up by your main job. The exact amount depends on your total income, your tax code and whether the work is employed or self-employed. Figures are current for 2026/27.
Why a Second Job Is Taxed Differently
HMRC gives you one personal allowance — £12,570 tax-free a year in 2026/27 — normally attached to your main job through your tax code, usually 1257L. Because it is already used, your second employer cannot apply it again, so tax on a second job starts from the first pound.
Your second employer will normally put you on a BR tax code, which taxes all of your pay at the basic rate of 20%. This guide to what the BR tax code means explains how it works, and the 1257L tax code is the code your main employer normally uses. Tell HMRC if you think the wrong code has been applied.
How Much Tax on a Second Job: The Rates for 2026/27
The bands are worked out on your total income from all jobs. For 2026/27:
| Taxable income (after personal allowance) | Rate |
|---|---|
| Up to £37,700 | 20% (basic rate) |
| £37,701 to £87,440 | 40% (higher rate) |
| Over £87,440 | 45% (additional rate) |
In practice, most tax on a second job is charged at 20% if your combined income stays below £50,270 a year (£12,570 personal allowance plus the £37,700 basic-rate band). Above £50,270 the slice of your second job over that line is taxed at 40%, and above £125,140 at 45%. One point that catches people out: once total income passes £100,000, the personal allowance shrinks by £1 for every £2 above that figure, disappearing entirely at £125,140.
Worked Example: A £30,000 Main Job and an £8,000 Second Job
Example: you earn £30,000 a year in your main job and £8,000 in a second job. Your main employer uses your £12,570 personal allowance, so you pay 20% on the remaining £17,430 (£3,486). Your second employer uses a BR code, so the whole £8,000 is taxed at 20% — £1,600 a year, about £133 a month. Your combined income of £38,000 is below £50,270, so nothing is taxed at 40%. This is the most common position: a flat 20% on the second job, with nothing extra to pay at the end of the year.
When a Second Job Pushes You Into the 40% Band
Example: you earn £45,000 in your main job and £12,000 in a second job — £57,000 in total. Your basic-rate band runs out at £50,270, so £5,270 of your second job is taxed at 20% (£1,054) and the remaining £6,730 at 40% (£2,692) — £3,746 for the year. The BR code alone would only collect 20% on the whole £12,000 (£2,400), so you would owe HMRC the extra £1,346 — usually collected by changing your tax code the following year, or through Self Assessment. See our guide to Self Assessment deadlines for when a return is due.
National Insurance on a Second Job
National Insurance works differently from Income Tax: it is calculated separately for each job, not on your combined income. In 2026/27 you pay no employee National Insurance on earnings up to £12,570 a year in each job, 8% between £12,570 and £50,270, and 2% above that. So a second job paying £8,000 a year attracts no employee National Insurance at all, while one paying £20,000 attracts 8% on £7,430 — about £594 a year.
Your second employer also pays employer National Insurance at 15% above £5,000 a year — the employer’s cost, not yours.
Tax Codes to Watch on a Second Job
- BR — the normal code for a second job: 20% on all pay, no personal allowance. Correct for most people whose main job uses the allowance.
- D0 — 40% on all pay, for combined income well into the higher-rate band. If your total income is under £50,270, you are overpaying.
- D1 — 45% on all pay, for total income above £125,140.
- 0T — no personal allowance, taxed across the bands. Often an emergency code used when your employer has no P45 or starter information.
Check the code on every payslip from your second job and update your details in your Personal Tax Account if it looks wrong — a wrong code can run for months. Our guide to PAYE and payroll basics explains how tax codes are set and how PAYE collects the tax each payday.
If Your Second Job Is Self-Employment
If your second job is freelance work, a side business or gig work rather than employment, different rules apply. You must register as self-employed with HMRC and report the income through Self Assessment. The first £1,000 of trading income a year is covered by the trading allowance and is tax-free; above that, you pay Income Tax on the profit at your marginal rate, plus Class 4 National Insurance of 6% on profits between £12,570 and £50,270 and 2% above that. Keep records from day one — see our guide to allowable expenses for self-employed people.
How to Check You Are Paying the Right Tax on a Second Job
- Check every payslip — the tax code, the tax deducted and the year-to-date figures from both jobs.
- Add up your total income. If it is heading over £50,270, expect some of your second job to be taxed at 40% — and budget for a bill if you only pay 20% through PAYE.
- Use your Personal Tax Account. It shows the income HMRC holds for you, your tax code and any underpayment being collected.
- Keep your P60s. Both employers issue one after 5 April; together they show your total pay and tax for the year.
- Student loan repayments are also based on total income across both jobs, so a second job can push you over your plan’s threshold even if neither job does on its own.
Frequently Asked Questions
Do I pay tax on a second job if I earn under £12,570 in total?
If your combined income is under £12,570, you should pay no Income Tax — but a BR code will still take 20% from your second job’s pay each month. HMRC should refund the overpayment, usually by correcting your tax code.
Is tax on a second job always 20%?
Not always. It is 20% while your combined income stays within the basic-rate band, but any part above £50,270 is taxed at 40%, and above £125,140 at 45%.
Do I pay National Insurance on a second job?
Only on the earnings from that job above £12,570 a year — National Insurance is worked out per job, so a small second job can attract none at all.
Do I need to tell HMRC about a second job?
Your employer tells HMRC when you start, through PAYE, so you usually do not need to do anything — just check your tax code. If the second job is self-employment, you must register with HMRC and file a Self Assessment return.
If a second job has left you with the wrong tax code or an unexpected bill, we can help you sort it out. See our services or contact us — email info@financialaccountingfirm.co.uk.
This article is general information, not personal tax or financial advice.
