Key takeaways
- Your £12,570 personal allowance can only be used once, so your second job is taxed from the first pound: BR takes 20% of everything, D0 takes 40%.
- Total income tax on £30,000 plus £10,000 across two jobs is exactly what you would pay on £40,000 in a single job.
- National Insurance is charged per job, not per person, so each job gets its own £12,570 threshold — a second job under £12,570 pays no NI at all.
- You can ask HMRC to split your personal allowance between two jobs, which smooths out your monthly pay.
Your second job is taxed from the first pound because your £12,570 personal allowance can only be used once, and your main job already uses it. BR takes 20% of everything; D0 takes 40%.
You take a second job — weekends, evenings, a few shifts a month — and the first payslip is a shock. You earned £800 and kept barely £640. No personal allowance, no tax-free slice, just 20% gone from the first pound. It feels like a mistake. It is not. It is the BR tax code doing exactly what it is designed to do, and once you see the whole picture it usually turns out fair.
One allowance, two jobs
Everyone gets a personal allowance of £12,570 a year — the slice of income you pay no tax on. But it is per person, not per job. When you have two jobs, HMRC has to decide which employer gets to apply it. The answer is almost always your main job, the one that pays you more. That job gets your normal code — usually 1257L — and the second job gets a flat code with no allowance at all.
BR means basic rate: 20% on every pound, no allowance. D0 means higher rate: 40% on every pound, no allowance. There is also D1 at 45%, for the rare case where your combined income is in the additional-rate band. Which one you get depends on your total income: BR is the default, and HMRC moves you to D0 when your main job alone takes you into the higher-rate band — roughly, when your main salary passes £50,270.
The numbers: £30,000 main job + £10,000 second job
Here is the full picture from the two jobs tax calculator, with no pension and no student loan:
| Job 1 (£30,000, 1257L) | Job 2 (£10,000, BR) | Combined | |
|---|---|---|---|
| Personal allowance | £12,570.00 | £0.00 | £12,570.00 |
| Income tax | £3,486.00 | £2,000.00 | £5,486.00 |
| National Insurance | £1,394.40 | £0.00 | £1,394.40 |
| Take-home pay | £25,119.60 | £8,000.00 | £33,119.60 |
Two things stand out. First, the total income tax — £5,486.00 — is exactly what you would pay on £40,000 earned in a single job.
You are not worse off for having two jobs; the allowance was just used on Job 1 instead of being spread around.
Second, the National Insurance is lower than on a single £40,000 salary: £1,394.40 instead of £2,194.40. That is because National Insurance is charged per job, not per person, so each job gets its own £12,570 threshold — and a second job under £12,570 pays no NI at all.
When BR is wrong
BR is correct when your main job uses the whole allowance and the basic-rate band. It is wrong in two common cases. The first: your main job is small. If Job 1 pays £8,000 and Job 2 pays £20,000, the allowance should arguably sit on Job 2 — but HMRC usually still puts it on the job you had first, and the year-end reconciliation sorts the total out. You are not overtaxed over the year; your monthly pay just looks lopsided. The second: you left a job mid-year. Your old employer's code can linger, or your new employer puts you on BR while HMRC catches up, and a few months of 20%-on-everything follow. Again, the total usually corrects itself — but check your Personal Tax Account if it drags on past two or three months.
D0 is wrong more often than BR. HMRC sets D0 when it thinks your main job takes you into the higher-rate band, but if your main salary is, say, £45,000, you are not a higher-rate taxpayer at all — and D0 on the second job takes 40% of money that should be taxed at 20%. That overpayment does come back, either through your tax code or a refund, but it can take months. If you are on D0 and your main job pays under £50,270, call HMRC: it is a five-minute fix.
Can you split the allowance?
Yes. You can ask HMRC to split your personal allowance between two jobs — for example, £8,000 on one and £4,570 on the other — which smooths out your monthly pay. It rarely changes the total tax you pay over the year, which is why most people do not bother. It is worth doing if the lopsided months cause you real cash-flow trouble, or if one job is seasonal and the other is steady. The split is arranged through HMRC, not through your employers, and it takes a few weeks to show up on your payslips.
National Insurance: the part people miss
The NI side of two jobs is genuinely good news, and it is the part nobody tells you about. Each employment has its own primary threshold of £12,570 a year (£242 a week), so a second job under that line pays zero National Insurance. Even above it, the 8% only applies to the slice over the threshold for that job. The only wrinkle is the upper earnings limit: if one job alone passes £50,270, you can end up paying the 2% additional rate on the wrong slices across two jobs, and reclaiming it takes a letter to HMRC. For most two-job workers earning under £50,270 combined, NI is simply lower than it would be on one job.
Two jobs, your pension and your benefits
Tax is not the only thing that splits across two jobs. Pensions do too, and the rules are less generous than the NI rules. Each job enrols you separately for auto-enrolment, and each job tests the £10,000 earnings trigger separately: a second job paying £8,000 a year does not trigger auto-enrolment on its own, even if your combined income is £38,000. You can ask to opt in, and your employer must enrol you if you do, but it does not happen automatically. And each job's pension is worked out on that job's qualifying earnings (£6,240–£50,270), so a second job under £6,240 accrues no auto-enrolment pension at all. If you want pension on both jobs, you have to arrange it — it will not arrange itself.
Benefits are the mirror image: most are tested on combined income, not per job. Universal Credit, for example, looks at your total earnings across all jobs, so a second job reduces your award in the same way a pay rise would. Statutory Sick Pay and Statutory Maternity Pay, on the other hand, are per employment: you can qualify for SSP from one job and not the other, and SMP is worked out separately for each employer, with the £129-a-week earnings floor applied to each job on its own. That can be good news — two small jobs that each pass the floor can mean two SMP entitlements — but it also means a second job that pays under the floor gives you nothing. The pattern to remember is simple: tax and NI are per job, benefits are mostly combined, and statutory pay is per job. When in doubt, check each scheme on its own terms rather than assuming one rule covers everything.
Reclaiming tax you overpaid
Two jobs are one of the most common reasons people overpay tax, and the money is reclaimable — but only if you notice. The usual story is the wrong split: HMRC gives your whole allowance to the main job and puts the second job on BR, which is right when the main job uses the full allowance. But if the main job pays less than the allowance — say £9,000 a year — then £3,570 of allowance is wasted on a job that does not need it, while the second job pays 20% on income that should have been tax-free. That is £714 a year overpaid. The fix is a split code: ask HMRC to move the unused slice to the second job, and HMRC will issue new codes to both employers. The overpaid tax for the current year is usually refunded through payroll once the new code arrives; for earlier years, HMRC sends a P800 calculation or you claim through your Personal Tax Account.
The other common overpayment is the opposite direction: the second job is put on a cumulative code with a full allowance by mistake, and you underpay for months until HMRC catches up with a demand. Both errors come from the same root — nobody told HMRC there were two jobs. The P46 (now the starter checklist) you fill in when you start a job asks exactly this, and answering it wrong is how the wrong code is born. If you have two jobs, check your Personal Tax Account once a year: it shows every code HMRC holds for you, and it is the fastest way to spot a split that no longer matches your pay.
What to check on your payslips
Three things. First, your main job should show 1257L (or your correct personal code) — if it shows BR, your allowance has gone missing entirely. Second, your second job should show BR unless your main job pays over £50,270, in which case D0 is right. Third, add up the tax across both jobs and compare it with the take-home pay calculator run on your combined salary: over the full year the totals should match within a few pounds. If they do not, something is wrong with a code, and HMRC's Personal Tax Account will show you which one.
Check your two-job tax
Add up the tax across both jobs and compare it with the take-home pay calculator run on your combined salary — over the full year the totals should match within a few pounds.
Figures from the 2026/27 rates, last checked against GOV.UK on 5 November 2026. See all the rates on UK tax rates 2026/27. Next in this series: Maternity pay, explained: SMP week by week.