How BR, D0 and other codes apply when you have more than one job — and why your yearly tax stays the same.
When you have more than one job, your employers operate Pay As You Earn (PAYE) separately. HMRC decides which job gets your Personal Allowance — the £12,570 you can earn tax-free in 2026/27. Your other job or jobs are usually taxed on all income without any allowance.
The critical point to understand: splitting your Personal Allowance between jobs does not change the total tax you pay over the year. It only affects how the tax is collected through your monthly or weekly pay cheques.
Let's walk through a simple example, assuming your only income comes from two jobs and you're in England, Wales or Northern Ireland.
Suppose Job A pays £30,000 a year and gets the full Personal Allowance. Your Job A tax for the year looks like this:
Job B pays £10,000 and is coded BR. All £10,000 is taxed at 20% — £2,000.
Your total tax across both jobs is £5,486. If you instead combined the income of £40,000 in a single calculation, the tax would be identical: £40,000 minus £12,570 equals £27,430, and £27,430 at 20% is £5,486. The BR code simply collects the correct amount without knowing about your other job.
If your combined income crosses the 40% threshold, HMRC may issue a D0 code for your second job. At that point, all income from that job is taxed at 40%. Again, the yearly total matches what you'd owe on combined income — it just collects it earlier in the year.
For a second job earning £15,000 alongside a main job earning £45,000, your total is £60,000. The first £50,270 of combined income is taxed at 20%, and the remaining £9,730 at 40%. Your second job at D0 taxes all £15,000 at 40%, but the main job's tax is reduced slightly to compensate. The overall figure remains correct.
HMRC usually chooses the job with the highest income for your Personal Allowance. That's the most efficient setup because it keeps more tax back until later in the year — but the final bill is the same.
You can ask HMRC to split your allowance differently, for example putting a portion on a second job. This won't reduce your tax. It only changes the timing of deductions, which some people find easier to manage.
If you've started a new job and your tax code looks off, you can update your details online:
Student loan repayments work separately from Income Tax. Your second job will also deduct student loan repayments if your income from that job exceeds the relevant threshold. Company benefits, like a workplace pension, are deducted independently by each employer.
If you receive taxable benefits from one job — such as a company car — those are typically added to that job's tax code rather than spread across your employments.
If your tax codes were never quite right, HMRC checks your total income for the year after 5 April. If you've overpaid, they'll refund you, often through your tax code for the following year. If you've underpaid, they may collect the difference through a future code adjustment.