Second Job Tax: How It's Taxed and How to Stop Overpaying

There is no special, higher rate of tax on a second job. Your two wages are added together and taxed under the normal Income Tax rules, but because each employer runs PAYE separately, HMRC has to decide which job gets your £12,570 Personal Allowance — and that decision is where most over- and underpayments come from. Typically the main job keeps the allowance and the second job is put on a BR code, taxing every pound at 20%.

Key points

• Income Tax looks at your total income from both jobs: £12,570 tax-free, then 20% on the next £37,700 of taxable income (different bands in Scotland).
• National Insurance is worked out separately for each job, so two smaller wages can mean less NI than one large one.
• A BR code on the second job is correct only if your main job already uses the whole Personal Allowance and you stay a basic-rate taxpayer.
• If your main job pays less than £12,570 you can ask HMRC to split the allowance across both jobs instead of waiting for a refund.
li>If the two jobs together push you over £50,270, BR under-collects tax and HMRC usually sends a P800 or Simple Assessment after the tax year ends.

Taxed more on a second job?

No — the rate does not change because the income comes from a second employer. For 2026/27 in England, Wales and Northern Ireland the arithmetic on your combined income is:

Scottish taxpayers pay Scottish rates on non-savings income: 19% starter on the first £3,967 of taxable income, 20% basic to £16,956, 21% intermediate to £31,092, 42% higher to £62,430, 45% advanced to £125,140 and 48% top rate above that.

Where a second job genuinely does change the outcome is National Insurance. Class 1 NI is charged per employment, per pay period, not on your combined pay. Each job gets its own £12,570-a-year primary threshold (about £1,047.50 a month), so:

• Two jobs paying £10,000 and £6,000 → no NI at all, because neither crosses the threshold.
• One job paying £16,000 → NI of (£16,000 − £12,570) × 8% = £274.40.

The same effect works at the top: because the 8% rate stops at £50,270 in each job, someone earning £46,000 plus £10,000 pays 8% on most of the second job's pay only if that job crosses its own threshold — in this case it does not, so NI on the second job is nil. (Employers that are connected or trading in association must add your earnings together for NI, so this does not work with two jobs for the same group of companies.)

Splitting the allowance

HMRC gives the Personal Allowance to one job by default — normally the one it sees as your main employment. That is fine if your main job pays more than £12,570. It is expensive if it does not.

Worked example 1: BR is correct

Main job £30,000 on code 1257L, second job £8,000 on BR.

• Main job: (£30,000 − £12,570) × 20% = £3,486
• Second job: £8,000 × 20% = £1,600
• Total deducted: £5,086
• Correct liability: (£38,000 − £12,570) × 20% = £5,086

Nothing to fix. The allowance is fully used in job one, and all the second job's pay falls in the 20% band.

Worked example 2: BR overtaxes you

Main job £10,000 on code 1257L, second job £6,000 on BR.

• Main job: £10,000 is below the allowance → £0 tax
• Second job: £6,000 × 20% = £1,200
• Correct liability: (£16,000 − £12,570) × 20% = £686
• Overpaid: £514

The unused £2,570 of allowance is stranded in the main job. Ask HMRC to split it: roughly £10,000 to job one (code 1000L) and £2,570 to job two (code 257L). Job two then pays (£6,000 − £2,570) × 20% = £686, and the deductions are right in real time instead of being refunded a year later.

A Scottish taxpayer in the same position would owe even less — £3,430 of taxable income all sits in the 19% starter band, giving tax of £651.70 — so an SBR code at 20% over-deducts by £548.30.

You can model your own split with the second job tax calculator before you ring HMRC, so you know what allocation you are asking for.

BR, D0 and split codes

The code on your second payslip tells you exactly what assumption HMRC has made.

Scottish codes carry an S prefix: SBR (20%), SD0 (21%), SD1 (42%), SD2 (45%) and SD3 (48%). Welsh codes carry a C prefix and currently mirror the rest-of-UK rates. If a code ends in W1 or M1 it is non-cumulative, which means the job is being taxed on that pay period alone — common in the first month of a new second job and a frequent cause of a temporary overdeduction.

Telling HMRC

You do not fill in a separate form. When you start the second job, your new employer will ask you to complete a starter checklist. Tick the statement that says you have another job or receive a pension (Statement C on the current version) — that is what produces the BR code and stops you accidentally claiming the allowance twice, which would create an underpayment.

After your first payday the employer reports your pay to HMRC through the Full Payment Submission, and HMRC issues a code for each employment. You should then:

1. Check both codes in your Personal Tax Account or the HMRC app, and confirm which job HMRC has treated as the main one.
2. Ask HMRC to move or split the allowance if your main job pays less than £12,570, or if the jobs have swapped over and the larger one is now on BR.
3. Check the estimated annual pay HMRC is using for each job. Codes are built on estimates, and a stale estimate is the second-biggest cause of a wrong code.

You can update employment details and estimated pay online through your Personal Tax Account on GOV.UK, or call the Income Tax helpline on 0300 200 3300.

If you leave one of the jobs, tell HMRC promptly — otherwise the allowance may stay attached to a job with no pay running through it while your remaining job keeps a BR code.

When it creates a bill

BR is a flat 20%. The moment your two jobs together cross £50,270, that flat 20% is too little, and the shortfall usually surfaces after 5 April.

Worked example 3: the classic P800

Main job £46,000 on 1257L, second job £10,000 on BR.

• Main job deducts: (£46,000 − £12,570) × 20% = £6,686
• Second job deducts: £10,000 × 20% = £2,000
• Total deducted: £8,686
• Correct liability: £37,700 × 20% = £7,540, plus (£56,000 − £50,270) × 40% = £2,292 → £9,832
• Underpaid: £1,146

Neither employer did anything wrong. Each applied the code it was given, and neither could see the other's payroll. When HMRC reconciles the year it will issue a P800 or Simple Assessment and normally collect the £1,146 by reducing next year's tax code. If you spot it during the year, HMRC can switch the second job to D0, or cut the allowance on the main job, so the tax is collected as you earn.

Other situations where a second job tips you into a bill or a return:

• Total income over £100,000. The Personal Allowance drops by £1 for every £2 above £100,000 and disappears at £125,140, creating an effective 60% marginal rate in that band.
• Child Benefit. The High Income Child Benefit Charge starts once the higher earner's adjusted net income passes £60,000 and takes back all the benefit at £80,000.
• Self-employed second income. A side business is not PAYE at all: the first £1,000 is covered by the trading allowance, above that you register for Self Assessment and pay Income Tax plus Class 4 NI at 6% on profits between £12,570 and £50,270.
• Student loan deductions. These are calculated per employment against the repayment threshold, so two jobs can produce smaller deductions than one combined wage.

If any of this sounds familiar, run the numbers rather than assume. Our underpaid tax check walks through the most common PAYE mismatches — including a BR code on the wrong job — and tells you whether you are likely owed a refund or facing a bill.

What to do next

Start with your payslips: note the tax code on each job and the pay to date. Then put both figures into the second job tax calculator to see the tax and NI you should be paying across the two employments, and compare it with what has actually been deducted. If there is a gap, use the underpaid tax check to work out which side of the line you are on before you contact HMRC — a five-minute code correction is far cheaper than a surprise P800 next autumn.