If you take a second job in the UK, your second income is taxed at a flat rate — usually 20% — with no Personal Allowance applied, because your allowance is already being used by your main employer. This can feel like a high deduction, but it is correct: you only get one Personal Allowance.
Why Your Second Job Is Taxed Differently
Each UK taxpayer gets one Personal Allowance of £12,570. Your main employer uses this to calculate your tax, meaning your primary income is taxed normally. Your second employer receives a BR (Basic Rate) tax code from HMRC, meaning they deduct 20% from every pound you earn — no allowance is applied.
Higher Rate on Second Job?
If your combined income from both jobs exceeds £50,270, HMRC may issue a D0 code to your second employer, meaning 40% is deducted on all second-job earnings. This happens when HMRC knows your main salary already uses the basic rate band.
What About National Insurance?
NI is calculated separately for each job. Each employer deducts NI independently based on that job's earnings. If your earnings from each job are below the NI threshold (£12,570/year), you may pay no NI on the second job at all — even if your combined income is high.
End of Year Reconciliation
HMRC reconciles your total tax position after the tax year. If you've overpaid due to the BR code (common if your total income stays within the basic rate band), you'll receive a P800 refund automatically or can claim early through your Personal Tax Account.
Self-assessment required? If your combined employment income exceeds £100,000, or you have untaxed income above £1,000, you must file a Self Assessment return.
Calculate your take-home pay
Use PayKeep's free calculator for your exact figures — pension, student loan, tax code and all.
→ Calculate Second Job Tax