Quick answer: A BR tax code takes 20% from every pound of your second-job pay, so you only owe extra if your combined taxable pay passes £50,270 in 2026/27 (England, Wales and Northern Ireland). For every £1 above that line you owe another 20p, because that slice should have been taxed at 40%. HMRC usually collects the shortfall through your tax code, in equal instalments over 12 months from the start of the next tax year, if you are paid through PAYE and owe under £3,000.
This guide covers two employed jobs paid through PAYE for the 2026 to 2027 tax year (6 April 2026 to 5 April 2027). Scotland has different bands, so it gets its own section below. It is general information, not personal tax advice.
What do BR and D0 mean on a second job?
On a BR code, your second employer takes the basic rate of 20% from everything you earn there. On D0 it takes the higher rate of 40%. You only get one Personal Allowance, and HMRC normally gives it to the job that pays you most, usually under code 1257L. The other job is then put on BR, D0 or D1, and GOV.UK says which one depends on your total income across all sources for the year.
| Taxes all pay from that job at | England and Northern Ireland | Scotland | Wales |
|---|---|---|---|
| Basic rate | BR (20%) | SBR (20%) | CBR |
| Higher rate | D0 (40%) | SD1 (42%). SD0 is the 21% intermediate rate | CD0 |
| Additional rate | D1 (45%) | SD2 (45%) or SD3 (48%) | CD1 |
These come from GOV.UK's guide to what your tax code means. A BR code is not a penalty. It is HMRC's way of saying "the allowance is already used on your other job, so tax every pound from this one."
Why does a BR code lead to a tax bill?
Because BR is a flat 20%, but Income Tax only switches to 40% when your total income passes £50,270. That is the £12,570 Personal Allowance plus £37,700 of basic rate band, and GOV.UK's rates page shows the £50,270 line. Neither employer sees the other's payroll. Each one applies the code HMRC gave it, so the second employer keeps taking 20% even on pay that sits above the line.
The shortfall is simple: 20% of your combined taxable pay above £50,270. It is not 40% of your second job. It is the missing 20% on the slice that crossed the line.
Here is how that grows if your main job pays £48,000 and your second job pays more and more (England, 2026/27):
| Second-job pay | Combined pay | Above £50,270 | Underpaid on a BR code |
|---|---|---|---|
| £1,000 | £49,000 | £0 | £0 |
| £2,270 | £50,270 | £0 | £0 |
| £3,500 | £51,500 | £1,230 | £246 |
| £6,000 | £54,000 | £3,730 | £746 |
| £10,000 | £58,000 | £7,730 | £1,546 |
If your main job already pays more than £50,270 on its own, the whole of the second job belongs in the 40% band, so a BR code under-collects 20% of every pound. A £55,000 main job plus £3,500 on BR leaves a £700 bill.
"Combined pay" means taxable pay. Pension contributions taken before tax (net pay or salary sacrifice) lower it, and other taxable income, such as savings interest above your allowance or a company car, adds to it.
How much will you owe? A worked example for 2026/27
Take a main job paying £48,000 on code 1257L and a second job paying £3,500 on code BR, in England.
| Tax | |
|---|---|
| Main job: (£48,000 minus £12,570) × 20% | £7,086 |
| Second job on BR: £3,500 × 20% | £700 |
| Deducted through payroll | £7,786 |
| Correct tax on £51,500: £37,700 × 20% + £1,230 × 40% | £8,032 |
| Underpaid | £246 |
The £246 is £1,230 (the pay above £50,270) × 20%. Put £51,500 into MySums' take-home pay calculator and its Income Tax line reads £8,032, so you can compare any combined figure of your own against what both payslips say you have paid. The calculator treats it as a single salary and does not model pension contributions, which is fine here because the sum is only checking the total.
Will HMRC switch a BR code to D0 during the year?
It might, but you cannot count on it, and D0 can take too much. HMRC sets the code from its estimate of your total income, and a MoneySavingExpert forum reply to someone in exactly this position described the usual result as BR on the new job plus a small adjustment to the code on the existing one. Treat that as one person's experience, not a rule.
D0 is not automatically the fix, because it taxes every pound of the second job at 40% even when only part of it is above the line. In the example, D0 on the £3,500 would take £1,400 instead of the £946 actually due, so you would overpay by £454 and wait for a refund after the year ends.
How does HMRC collect the tax you owe?
Usually through your tax code, without you doing anything. After 5 April, HMRC gets the full-year figures from both employers and sends either a P800 tax calculation or a Simple Assessment letter. GOV.UK says these go out from June to March, over the following tax year.
If you are paid through PAYE, earn enough above your allowance to cover the debt and owe under £3,000, HMRC takes it through your tax code, normally spread evenly across the 12 months after the new tax year begins. You can pay it off sooner if you prefer.
The code change works by grossing the debt up at your tax rate and cutting your tax-free amount by that figure, a method the Low Incomes Tax Reform Group sets out. For the £246 in the example:
- £246 ÷ 20% = £1,230 off your tax-free amount
- £12,570 minus £1,230 = £11,340, so the main job's code becomes 1134L
- The extra tax is about £20.50 a month for 12 months (£246 ÷ 12)
Your coding notice shows the exact figure HMRC has used. If a bill would cause hardship, contact HMRC and ask to spread it. LITRG says the usual maximum is three years. If HMRC spots the problem part-way through the year, it may adjust your current code instead, but that normally does not happen after 5 January.
If you owe more than £3,000, or the tax cannot be taken from your income, you will get a Simple Assessment letter and pay HMRC directly.
How do you avoid a bill at the end of the year?
Tell HMRC your realistic total income early, so the tax is collected a little at a time as you go.
- Add up what both jobs will pay in the whole tax year, plus any other taxable income.
- If the total is over £50,270, update your estimated income in the PAYE section of your Personal Tax Account or the HMRC app. HMRC says it will tell you and your employer a new code within 15 working days, and on monthly pay it should show on your next or following payslip.
- When you start a second job, say on the starter checklist that you already have another job. You will not have a P45 to hand over, because you have not left the first one.
- Check which job holds your allowance and what code each employer is using on your payslips.
- Consider a pension contribution taken before tax. In the example, £1,230 into a pension through salary sacrifice brings your taxable pay back to £50,270 and removes the bill. MySums' salary sacrifice calculator shows the effect, and the pension tax relief guide explains how the different routes work.
- If none of that is practical, set aside 20p of every £1 you earn above the line.
If the codes look wrong and you are not sure why, MySums' payslip guide walks through each line. For how HMRC splits the allowance, National Insurance and side income, see second job tax explained.
How is it different in Scotland and Wales?
In Scotland the 42% higher rate starts earlier, so the bill can too. Scottish Income Tax for 2026 to 2027 is 19% on income from £12,571 to £16,537, 20% to £29,526, 21% to £43,662, 42% to £75,000, 45% to £125,140 and 48% above that. A second job on SBR is taxed at a flat 20%.
Take a Scottish main job paying £42,000 and a second job paying £3,500 on SBR:
| Tax | |
|---|---|
| Deducted through payroll (main job £5,971.07 + SBR £700) | £6,671.07 |
| Correct tax on £45,500 | £7,092.05 |
| Underpaid | £420.98 |
The first £1,662 of the second job should have been taxed at 21% and the last £1,838 at 42%, so SBR falls short on both parts. Switch the take-home pay calculator to Scotland and enter £45,500 to see the £7,092.05 total. How HMRC would collect a Scottish debt through your code is set out on your own coding notice.
Wales has its own C-prefixed codes (CBR, CD0 and CD1). The logic is the same: the code taxes the whole job at one rate, and any difference is settled after the year ends.
What does this guide not cover?
Self-employed side income does not go through a tax code. Above the £1,000 trading allowance it is declared on a Self Assessment return, as GOV.UK's guidance explains. Income over £100,000, where the Personal Allowance starts to taper, also changes the sums.