Why is my second job taxed so much?

The short answer: your second job isn’t taxed at a higher rate. Your £12,570 tax-free allowance is normally given to your main job, so everything from the second job is taxed at 20% from the first pound. If your main pay is already above the allowance, that is the right amount. If your total income is low, you may be paying too much and can fix it.

Why the tax looks heavy

Your main job uses the allowance: that is why you pay tax only on pay above £12,570. HMRC gives the second job a basic rate code (BR), which taxes every pound at 20%. A second job paying £6,000 a year loses £1,200 in tax, which looks heavy because there is no tax-free slice on it. In fact it is the same tax you would pay if the £6,000 were part of one bigger salary.

On a main job of £30,000, the tax on a second job is right at every level up to the higher-rate threshold:

When you really are overtaxed

The problem is when your total income is low. Say your main job pays £8,000 and your second pays £6,000: your total is £14,000. The correct tax is £286, but the second job takes £1,200 at 20%. That’s £914 too much, because most of your allowance was never used. The fix is to ask HMRC to split your allowance between the two jobs so each has its share, or to reclaim the overpayment at the end of the year.

When it is more than 20%

If your combined income passes £50,270, the pay above that is taxed at 40%. HMRC may give the second job a D0 code. Between £100,000 and £125,140 the allowance also shrinks, which creates a 60% effective rate; see the 60% tax trap.

National Insurance and student loans

National Insurance is worked out separately for each job: 8% on pay above £12,570 in that job, and 2% above £50,270. A small second job often pays none. Student loan repayments are also worked out per job, so you can repay on both even if neither alone would be above the threshold, and you may be due a refund at the end of the year.

How to fix it

1. Check the tax code on each payslip. See tax codes explained.
2. If your total income is under or near the allowance, contact HMRC through your personal tax account to split it between jobs.
3. If you have already overpaid, claim a refund for the tax year.

A worked example from two payslips

Main job £30,000, second job £6,000. The main job uses the allowance and pays £3,486 tax a year. The second job pays £1,200 at 20%. Together that is £4,686, which matches the correct tax on £36,000 of £4,686. Nothing has been overcharged. The second job also pays no National Insurance, because £6,000 is under the £12,570 threshold for that job.

How to split the allowance

If your two jobs are both small, ask HMRC to share the allowance. For example, two jobs that each pay £9,000 would see the second one taxed at 20% from the first pound under standard codes, even though your total of £18,000 is £5,430 over the allowance. The correct tax is £1,086, yet the standard codes would collect £1,800, all on the second job, because the first job is under the allowance. Splitting the allowance, for instance 629L on each job, lets each employer apply part of it, and the tax collected becomes close to the correct figure.

New starters: the checklist question

When you start the second job your employer asks if it is your only job. If you say it is your first or only job, you may be given the main code, and your allowance is used twice. HMRC then spots the overlap and changes your codes, which can mean a tax bill at the end of the year. If you say you have another job, you will get BR. The honest answer avoids a surprise later.

Side income that isn’t a second job

• Under £1,000 gross: the trading allowance covers it, and you don’t need to tell HMRC.
• Over £1,000: register for Self Assessment. Tax is worked out on your total income, and your allowance isn’t doubled.
• Gig work: platforms don’t take tax, so you need to track it yourself. See the self-employed tax calculator.

Scotland and Wales

Scotland has its own rates and bands, and Scottish tax codes start with S. Wales uses the same income tax rates as England, with a C prefix on the code.

This is general information, not tax advice. Figures are for 2026/27 in England, Wales and Northern Ireland. Scotland has different rates.