Second Job Tax: How It Works and How Much You Keep
Taking on a second job is increasingly common — whether for extra income, career development, or financial security. But the tax treatment of second job income surprises many people: because your Personal Allowance (£12,570 in 2025-26) is already allocated to your main job, all income from a second job is taxed from the first pound.
How second job tax codes work
Your primary employer uses your full Personal Allowance (code 1257L or equivalent). HMRC tells your second employer to use a flat-rate code — usually BR (Basic Rate), which taxes all income at 20%. This is correct — you are not being penalised; you simply cannot claim the same allowance twice.
If your main job salary already puts you in the Higher Rate band (above £50,270), your second job income would be taxed at 40% (code D0).
Take-home from a second job at common income levels
| Second job income | Tax (BR 20%) | NI (8%) | Take-home |
|---|---|---|---|
| £2,000 | £400 | £0 | £1,600 |
| £5,000 | £1,000 | £194 | £3,806 |
| £8,000 | £1,600 | £434 | £5,966 |
| £10,000 | £2,000 | £594 | £7,406 |
| £15,000 | £3,000 | £944 | £11,056 |
| £20,000 | £4,000 | £1,394 | £14,606 |
Note: NI applies to the second job income above the Primary Threshold (£12,570 per year across all jobs — though each employer applies their own threshold, HMRC reconciles at year end). These figures assume the second job NI is also calculated on a per-job basis initially.
Are you paying the right amount of tax on a second job?
At the end of the tax year, HMRC reconciles your total income across all sources. If your combined income from both jobs means:
- Your total is below £12,570: you may be owed a refund (unused Personal Allowance)
- Your total is between £12,571 and £50,270: 20% on the taxable portion — BR should be correct
- Your total exceeds £50,270: some second job income may need to be taxed at 40%
Year-end tax reconciliation
HMRC will send a P800 tax calculation after the tax year ends if you have underpaid or overpaid. If you had a BR code on a second job but your combined income puts you in the basic rate band only, no further tax is due. If your total income crosses into the higher rate band, you will receive a bill for the difference.
Can you split your Personal Allowance between two jobs?
Yes. If you believe the split BR code is causing you to overpay (for example, your main job has low pay and does not use your full allowance), you can ask HMRC to split your Personal Allowance between the two employers. Contact HMRC on 0300 200 3300 to request this.
Frequently asked questions
How much tax do you pay on a second job?
All second job income is taxed at 20% with no Personal Allowance (BR code), plus 8% National Insurance on earnings above £12,570. On £10,000 from a second job, you take home approximately £7,406.
Do you always pay 20% on a second job?
If your first job salary is below £50,270, yes. If your first job puts you in the Higher Rate band (above £50,270 combined), second job income is taxed at 40% (D0 code).
Will I owe extra tax from a second job?
If BR (20%) is the correct rate for your band, no extra tax is due. But if your combined income crosses £50,270, HMRC will assess the higher rate on the excess — either through a code change during the year or a P800 reconciliation after April.