Second Job Tax Code Checklist 2026/27: Get It Right the First Time

Why Second Job Tax Codes Cause Confusion

When you have one job, HMRC applies your full personal allowance (£12,570 in 2026/27) against that income via your tax code, most commonly 1257L. Add a second job, and the system needs to decide how to split your personal allowance and tax bands across two separate payrolls — and by default, it usually assumes your main job already uses the full personal allowance, applying a flat-rate code to the second job instead.

This assumption is often correct, but not always — and getting it wrong in either direction means you either overpay tax during the year (getting it back later, but losing use of the money in the meantime) or underpay and face an unexpected bill.

The Common Second Job Codes

The Checklist: Is Your Second Job Code Actually Right?

1. Does your main job use your full personal allowance? If your main job pays £12,570 or more a year, it likely uses your full personal allowance, and a BR code on your second job is probably correct. If your main job pays less than that, a flat BR code on the second job is likely overtaxing you, since none of your unused personal allowance is being applied anywhere.

2. Is your combined income pushing you into the higher rate band? If your total income across both jobs comfortably exceeds £50,270 (where the higher rate band starts, after the £37,700 basic rate band above the £12,570 personal allowance), a D0 code on the second job may genuinely be correct — it's not automatically a mistake to see 40% tax on a second job's payslip.

3. Did you start the second job without a P45? If so, an emergency or 0T code is common initially, particularly if you didn't complete a starter checklist accurately. This should normally be corrected once HMRC receives full information, but it's worth checking your next few payslips to confirm the code updates rather than staying on an emergency basis indefinitely.

4. Have your circumstances changed mid-year? A pay rise, a change in hours, leaving one job, or starting a third income source can all mean a previously correct code becomes wrong partway through the tax year. Check your tax code after any income change, not just when starting a new job.

Worked Example: When BR Overtaxes You

Here, the main job only uses £8,000 of the £12,570 personal allowance, leaving £4,570 unused. Under a BR code, the second job pays 20% tax on the full £10,000 with no allowance — but correctly, £4,570 of that £10,000 should also be tax-free. This is a case where asking HMRC to split the personal allowance between both jobs (rather than applying it entirely to the main job) would reduce the total tax paid across the year.

How to Get It Fixed

1. Add up your total expected income from all jobs for the tax year.
2. Compare the tax code and expected code type against the checklist above.
3. If something looks wrong, contact HMRC via your Personal Tax Account, by phone, or by post, explaining your total income across all employments.
4. HMRC will issue an updated tax code to the relevant employer(s) — this should show on your next payslip after they receive it.
5. If you've overpaid earlier in the tax year before the fix, this is usually caught up automatically through the corrected code (which can apply extra allowance in later pay periods) or via end-of-year reconciliation — but don't assume; check your P60 and, if needed, request a review directly.