Tax Code Checker

Your tax code tells your employer how much tax-free income you are entitled to. The numbers represent your Personal Allowance divided by 10, and the letters indicate your situation. The standard code 1257L means £12,570 Personal Allowance with standard conditions.

The most common UK tax code is 1257L. This gives you the standard Personal Allowance of £12,570 for the 2025-26 and 2026-27 tax years — frozen until April 2031 (Autumn Budget 2025 extended the freeze by a further three years from the previous April 2028 end point). The L suffix means you are entitled to the standard tax-free allowance with no special circumstances.

A K code means you have untaxed income (typically company benefits, state pension, or owed tax from a previous year) that exceeds your Personal Allowance. The K number × 10 is added to your taxable income each year. For example K475 adds £4,750 to your taxable income before bands are applied.

An emergency tax code (W1, M1, or X suffix) is a temporary code HMRC applies when they lack full information about your income — common after a job change without a P45. It taxes each pay period independently (non-cumulative). You usually overpay until HMRC issues the correct code; you can claim back via your Personal Tax Account.

HMRC sends a P2 PAYE coding notice when circumstances change — new company benefit, second job, starting state pension, switching from Marriage Allowance, or revised estimated income. If you think your new code is wrong, update details in your Personal Tax Account or call HMRC on 0300 200 3300.

An S prefix (e.g. S1257L) means you pay tax at Scottish rates, which have more bands than the rest of the UK. Your Personal Allowance still works the same way — the number × 10 — but the bands above it differ, so the same salary and allowance can produce a different tax bill. On a £35,000 salary, our decoder estimates £4,501 of tax under S1257L versus £4,486 under the equivalent rUK code 1257L. Scotland also has its own flat-rate codes — SBR, SD0, SD1, SD2 and SD3 — which work like BR/D0/D1 but at Scottish rates. For example, SD2: all your income from this job or pension is taxed at the Scottish advanced rate.

W1 (week 1), M1 (month 1) and X mark an emergency tax code as non-cumulative — each pay period is taxed in isolation instead of averaging your Personal Allowance across the year. They typically appear when you start a new job or pension without giving your employer a P45, or when your circumstances change mid-year before HMRC issues an updated code. HMRC normally corrects the code automatically once it has full details, and any tax you overpaid on the emergency basis is refunded through your payroll (or via your Personal Tax Account) rather than needing a separate reclaim.

There is no single right answer — the correct code is the one that matches your circumstances. Start from the standard code (1257L, the £12,570 Personal Allowance divided by 10 with an L suffix) if you have one job, no taxable company benefits and no allowance transferred to or from a partner. Then adjust: an M or N suffix if you receive or give Marriage Allowance; an S or C prefix if you live in Scotland or Wales; BR, D0 or D1 on a second job or pension where the allowance is already used by your main income; 0T if HMRC has no details for you; and a K prefix if untaxed income outweighs the allowance. Earnings above £100,000 taper the allowance away, so a lower number is expected there. Decode your actual code above, then confirm it against HMRC's Check your Income Tax for the current year service, which shows the income, benefits and expenses HMRC used to build it.

Most codes are routine. A number with an L, M or N suffix — with or without an S or C prefix — is a normal cumulative code, and needs no action beyond checking the number looks right for your allowance. BR, D0 and D1 are normal on a second job or pension, because your allowance is being used elsewhere; they are a problem only if one appears on your main income. The codes worth a second look are 0T (HMRC has no details, so you get no allowance at all), any K prefix (untaxed income exceeds your allowance), and any code ending W1, M1 or X (emergency, non-cumulative). None of those is automatically an error, but each is worth confirming rather than assuming, because all three commonly leave you paying more tax now than you will owe for the year.

HMRC puts you on an emergency code when your employer has no previous pay and tax details for you — usually a new job started without a P45. The fastest fix is to hand your new employer the P45 from your previous job; if you do not have one, your employer collects the same information with HMRC's starter checklist. Otherwise HMRC updates the code itself once it has the details from your old and new employers, which can take up to 35 days from the day you start. You do not need to reclaim anything separately: once a cumulative code is applied, tax overpaid earlier in the same tax year comes back through your payroll.

Check and correct the underlying details first — employments, pensions, company benefits and expenses — in HMRC's Check your Income Tax service or the HMRC app; those details are what the code is built from, so correcting them is what changes the code. If the code does need to change, HMRC says it will tell you and your employer within 15 working days. The new code then shows on your next payslip if you are paid monthly, or by the third payslip if you are paid weekly, and any tax overpaid earlier in the same tax year is repaid automatically through payroll. If you would rather speak to someone, HMRC's Income Tax helpline is 0300 200 3300.

A K code appears when untaxed income — company benefits like a car or private medical insurance, State Pension (which is taxable but paid without tax deducted at source), or tax HMRC is collecting from a previous year — is worth more than your Personal Allowance. Since there's no allowance left to give you, HMRC instead adds the excess to your taxable pay. K475 specifically adds £4,750 (475 × 10) to your taxable income: on a £30,000 salary that means tax is calculated on £34,750 of taxable income, producing an estimated £6,950 of tax — about 23.17% of the £30,000 salary itself.