Tax on a Second Job UK — How Much Will I Actually Keep?

Thinking about taking a second job? The tax can feel brutal — but it's often not as bad as your first payslip suggests.

Why Your Second Job Seems Heavily Taxed

Your personal allowance (£12,570) is usually allocated entirely to your main job. This means your second job is taxed from the very first pound, typically with tax code BR (20% on everything). There's no tax-free amount.

Can I Split My Personal Allowance?

Yes! If your main job doesn't use your full personal allowance (because you earn less than £12,570 there), you can ask HMRC to split it between jobs. Call 0300 200 3300 or update through your Personal Tax Account. This ensures you're not over-taxed.

What If I'm Already a Higher Rate Taxpayer?

If your main job already puts you in the higher rate band (over £50,270 combined), your second job income will be taxed at 40%. In this case, your tax code should be D0 for 40% or D1 for 45%.

Will I End Up Owing Tax?

If your tax codes are set up correctly across both jobs, PAYE should handle everything. But if your total earnings push you into a new tax band that neither employer accounts for, you could get an underpayment notice from HMRC after the tax year. This is added to next year's tax code — you won't get a surprise bill.

Self-Employment as a Second Job

If your second income is self-employed (freelancing, gig work), you'll declare it on a Self Assessment tax return. The same marginal rate principle applies — it's taxed on top of your employment income. See our side hustle tax guide.