How to Check Your UK Tax Code is Correct

Your UK tax code is a short string — usually 1257L in 2026/27 — that tells your employer exactly how much Income Tax to deduct from your pay. Get it wrong and you’ll either overpay tax (refunded slowly) or underpay (demanded back next year). HMRC’s systems handle most codes correctly, but circumstances change: a new job, company benefits, claimed Marriage Allowance, a prior under-payment. Here’s how to check yours in five minutes.

Where to find your current tax code

Your tax code appears in at least three places:

1. Your most recent payslip. Look for a line labelled “Tax code” — it should show something like 1257L, 1257L W1, BR, D0, or a K-prefixed code. The suffix letters matter — see our tax code explainer for what each one means.
2. Your P60 (given annually after 5 April) or P45 (when leaving a job). Both show the code used at end of employment.
3. HMRC’s Personal Tax Account at gov.uk/personal-tax-account. Sign in with your Government Gateway ID — the dashboard shows the current code for every PAYE source of income.

If the codes differ between sources, the Personal Tax Account (PTA) is authoritative because it’s the HMRC system of record. Your payslip reflects what the employer received most recently from HMRC.

What your tax code should be (quick checklist)

Most UK employees in 2026/27 should see 1257L — the standard code for someone entitled to the full Personal Allowance of £12,570 with no adjustments. You should expect a different code if:

• You have a second job. The second job’s code is typically BR (20% from pound one), D0 (40%) or D1 (45% in England; or SD1–SD4 in Scotland). See our tax code 1257L explainer and BR tax code page.
• You claim Marriage Allowance. Your code becomes 1131N (you transferred £1,260 of PA) or 1383M (you received £1,260).
• You receive taxable company benefits (car, medical, gym). HMRC reduces the numerical part, e.g. 1100L, to recover the tax on those benefits through PAYE.
• You owe tax from a previous year. HMRC collects via a reduction in this year’s code.
• You’re Scottish-resident. Your code is prefixed S (e.g. S1257L) so your employer applies Scottish bands.
• You’re Welsh-resident. Code prefix is C (e.g. C1257L).
• You’re on an emergency code. W1, M1, or X suffix means the code applies week-by-week or month-by-month (no cumulative tax-free allowance). Common after starting a job mid-year. See our emergency tax page.

Step-by-step: is my code right?

1. Log in to your Personal Tax Account at gov.uk/personal-tax-account. You’ll need Government Gateway credentials — sign up if you haven’t; it takes 10 minutes with a passport or UK driving licence.
2. Click “Check your Income Tax”, then “Check your current tax code.”
3. Review the code’s breakdown — HMRC shows exactly what allowances were added/subtracted (benefits, state pension, outstanding tax owed, Marriage Allowance, etc.).
4. Compare against expected: start with £12,570 Personal Allowance, add/subtract any adjustments shown, divide by 10 — that’s your code’s number.
5. Check the suffix letter — L is standard, M is received-MA, N is transferred-MA, K means you have negative allowances (more adjustments than PA). Scottish residents have S prefix; Welsh residents C.

If the numbers match your expectations and circumstances, you’re fine. If they don’t, proceed to “What to do if it’s wrong.”

Red flags that your tax code needs review

Watch for these warning signs on your payslip:

• Income Tax is zero on a £30k+ salary with a regular monthly schedule. Likely on emergency code W1/M1 or NT — will be reconciled when HMRC catches up.
• You changed jobs and deductions jumped — the new employer may be on BR (no PA) until P45 is processed. Usually self-corrects within 1–2 pay cycles.
• Private medical or company car was added but your code didn’t change. HMRC may not know yet — they need a P11D from your employer (submitted by 6 July following the tax year).
• Your Marriage Allowance status changed (married, separated, one partner became a higher-rate taxpayer) but code didn’t update.
• You had a bonus or severance payment in a prior year that pushed you over the higher-rate threshold — HMRC may have reduced your code to recover unpaid tax.

What to do if it’s wrong

1. Don’t panic — tax-code errors are usually self-correcting within a year.
2. Gather evidence: P60, last 3 payslips, any P11D (benefits), evidence of the correct circumstances.
3. Use HMRC’s online service at gov.uk/tell-hmrc-about-change-of-details to update address, employment, benefits, marital status.
4. Call HMRC on 0300 200 3300 (8am–6pm Mon–Fri) if you can’t resolve it online. Have your NI number and tax code ready.
5. Write to HMRC (Pay As You Earn, HM Revenue and Customs, BX9 1AS) if you need to escalate — keep proof of posting.

If you’ve overpaid, HMRC usually refunds via PAYE (adjusted in a subsequent pay) or by cheque once the error is confirmed. If you’ve underpaid, HMRC collects via next year’s tax code — but if it’s a large amount (>£3,000) you may be asked to pay directly.

Use our salary calculator to confirm the numbers

Once you know your tax code, you can sanity-check the amount actually deducted from your pay. Put your gross salary into the salary calculator for the current tax year and compare the Income Tax figure against your payslip’s year-to-date total (pro-rated for the number of months elapsed in the tax year). Any mismatch > £20/month is worth investigating.

For Marriage Allowance specifically, try our Marriage Allowance calculator to confirm you’re getting the full £252 benefit.

Related

• All UK tax codes explained
• 1257L tax code — the standard code
• BR / D0 / D1 — second job codes
• K tax codes — what negative allowances mean
• Emergency tax codes (W1/M1/X)
• Salary calculator — verify your take-home

If you’re convinced the code is wrong and HMRC won’t fix it, the next step is a formal review — see the HMRC complaints process at gov.uk/complain-about-hmrc. Most issues resolve long before that stage.