4 May 2026
Do you pay more tax on a second job? UK tax explained
Working two jobs doesn't necessarily increase your total Income Tax bill, but National Insurance works differently, and it can all look confusing on your payslips. Here's how it actually works.
Short answer: having two jobs doesn't inherently increase your total Income Tax bill, because Income Tax is based broadly on your combined taxable income, regardless of how many jobs it comes from. National Insurance works differently: it's normally calculated separately for each job, so two jobs can sometimes mean paying more Class 1 National Insurance overall than the same total income from a single employer. It's usually your second payslip looking heavily taxed that causes the confusion, more than the underlying reality.
Why your second payslip looks heavily taxed
You only get one Personal Allowance (£12,570 for 2026/27), and it's usually allocated entirely to whichever job HMRC treats as your main one, normally the one you started first or that pays the most. Your second job then gets taxed from the very first pound, with no tax-free slice of its own, which makes it look far more heavily taxed than the first.
Tax codes you'll see on a second job
Which code your second job gets depends on how much of your Income Tax bands your main job has already used up:
- BR: all income from the second job taxed at the basic rate (20%)
- D0: all income from the second job taxed at the higher rate (40%)
- D1: all income from the second job taxed at the additional rate (45%)
These are the rest-of-UK codes. Scottish taxpayers see SBR, SD0, SD1, SD2, or SD3 instead, and Welsh taxpayers see CBR, CD0, or CD1, reflecting their own bands. See our guide to UK tax codes for the full list.
National Insurance with two jobs
National Insurance is usually calculated separately for each job against its own Upper Earnings Limit (£50,270 for 2026/27). If you're a high earner with more than one job, this can mean you pay more Class 1 National Insurance overall than someone earning the identical total from a single employer. If that applies to you, you can apply to HMRC to defer National Insurance on one of your jobs using form CA72A, so it's charged at the reduced 2% rate instead of the full rate.
A worked example
Say you earn £30,000 from your main job and £10,000 from a second job, £40,000 in total. Your main job uses the standard 1257L code: £17,430 is taxable after the Personal Allowance, taxed at 20%, coming to £3,486. Your second job is taxed entirely at the basic rate under a BR code: £10,000 at 20% comes to £2,000. Total Income Tax: £5,486.
Now compare that to earning the same £40,000 from a single job: £27,430 taxable after the Personal Allowance, all within the basic rate band, taxed at 20%, also coming to £5,486. Identical Income Tax, as long as the tax codes are set correctly. National Insurance is a separate calculation on top in both cases, and since £40,000 sits below the £50,270 Upper Earnings Limit either way, it also comes out the same here regardless of how the income is split.
When you might end up overpaying (and how to fix it)
Problems arise when the default allocation doesn't suit your situation, for example if your "second" job actually pays more than your "first". You can ask HMRC to move your Personal Allowance to whichever job makes more sense through your personal tax account. Any small over or underpayment that does occur usually self-corrects automatically, either through your tax code the following year or via a P800 calculation.
Our Income Tax Calculator and National Insurance Calculator can help you sanity-check what each of your jobs should be deducting. For more on reading your tax codes, see our guide to what UK tax codes mean.