Second Job Tax in the UK: What You Actually Pay on a Second Income

Two jobs don't mean more tax — but the second one starts at 20%

HMRC's arithmetic is simple: Income Tax is worked out on everything you earn added together, not on how many payslips you have. Someone on £25,000 from one job and someone on £15,000 from each of two jobs pay the same Income Tax for the year. That part of the system doesn't care how your income is split.

What changes is how the tax is collected along the way. You only get one Personal Allowance of £12,570 each year, however many jobs you hold, and PAYE normally attaches it to your main job. Your second employer is told to tax that job from the first pound — which is why the deduction on a second payslip often looks harsh next to the first.

The usual code on a second job is BR, D0 or D1. Each is an instruction to payroll: BR takes 20% of every pound, D0 takes 40%, D1 takes 45%. If neither job pays much, one of those codes may be collecting more than you owe; if your combined income reaches the higher-rate band, BR may be collecting too little. Both are fixable, and both are covered below. Our guide to tax on a second job explains the codes and how to split your allowance.

Why your second job has a different code from your first

When you start a second job, your new employer tells HMRC what they expect to pay you, and HMRC issues a code for that employment. Because your allowance is already being used by your main job, the code for the second one normally has no allowance in it. GOV.UK's guidance on having more than one job lists the codes you'll usually see: BR (all income taxed at the basic rate), D0 (higher rate) and D1 (additional rate).

If you live or work in Scotland or Wales the codes carry a prefix — S for Scottish, C for Welsh — and the rates behind them are different. The tax codes guide shows how a code is put together, and what is my tax code covers where to find yours.

Put the code and the pay from that job into the tax code calculator to see what it should cost you across the year and on each payslip. If you're on BR and want to know exactly what the code is charging, the BR tax code explainer works through it.

Worked example: £30,000 main job and £10,000 second job

Take someone earning £30,000 in a main job on 1257L and £10,000 in a weekend job on BR, in England, for 2026/27. The table shows what each job costs in tax and National Insurance, and what happens to the same £40,000 if it all comes from one employer.

National Insurance is counted job by job

The Income Tax totals in that table are identical — £5,486 either way — because your allowance and your bands are the same whoever pays you. The difference is National Insurance: £800 less when the pay is split between two employers. That isn't a loophole, it's how the rules are written.

Income Tax is pooled across your jobs, but National Insurance isn't. Each employer works out NI on the pay they give you, applying the primary threshold — £242 a week, roughly £12,570 a year — to that job alone. So the £10,000 weekend job sits below the threshold and pays no employee NI at all, even though the main job has already used up the same threshold.

Two exceptions matter. If you hold two jobs with the same employer, that employer should add the pay together and count NI on the total. And if two employers carry on business in association — sharing premises, staff, equipment or customers to a significant degree — HMRC can require the pay to be aggregated there too.

If you have more than one job and expect to earn enough that your NI would exceed the annual maximum, you can apply to HMRC to defer part of it rather than overpay and wait for a refund. GOV.UK's guidance on employees with more than one job sets out how employers are meant to handle the calculation.

When BR collects too little: the higher-rate gap

BR takes 20% whatever you actually earn. If your combined income pushes you into the higher-rate band — above £50,270 in 2026/27 — the second job has been under-taxed and you'll owe the difference for the year.

Say £45,000 in the main job on 1257L and £15,000 in the second on BR. Payroll takes £6,486 from the first and £3,000 from the second. The correct Income Tax on £60,000 is £11,432, so there is still money to find.

When BR collects too much

The opposite happens when your main job doesn't use the whole allowance. Earn £11,000 in a main job on 1257L and £9,000 in a second job on BR, and payroll takes £1,800 from the second job — but your total income of £20,000 only attracts £1,486 of tax for the year, so you've overpaid by £314.

You can ask HMRC to split your Personal Allowance between the jobs so neither is over-taxed, which is worth doing when both jobs pay under £12,570. Otherwise the overpayment comes back through payroll once the right code is in place, or through a P800 refund after the tax year ends.

Emergency codes on a new second job

You won't have a P45 for a job you've never had, and if you don't fill in the starter checklist HMRC may put you on an emergency code ending W1, M1 or X, or on 0T. Those take tax as if the pay were your only income, week by week, so the first payslips can look wrong in either direction.

Emergency codes normally correct themselves once HMRC has your details, and anything overpaid comes back through later payslips. Our emergency tax codes article explains what each code means and how long to wait before chasing it.

How to keep a second job taxed correctly

None of this needs a form if your details reach HMRC in time. The checks below take a few minutes and catch most second-job tax problems before they turn into a bill.

• Fill in the starter checklist for the new employer and make clear it's a second job — that's what prompts HMRC to issue BR or D0 rather than an emergency code.
• Check your tax codes in the HMRC app or Personal Tax Account: only one employer should be using 1257L at any one time.
• New employment details appear in your tax account about six weeks after your first payday, so check them then rather than assuming the code is right.
• If both jobs pay under £12,570, ask HMRC to split your Personal Allowance between them.
• Add your combined income into the take-home pay calculator to see the year's real position instead of judging it from one payslip.
• Keep payslips from both jobs until the year ends, when HMRC's P800 reconciles everything you've paid.