UK Payroll Tax Codes Deep Dive 2025/26 — 1257L, K, BR, D0, NT Explained

Anatomy of a tax code

A UK PAYE tax code is two parts: a number and one or more letters. The number is your annual Personal Allowance divided by ten. The letters tell PAYE software which calculation method to apply. For the 2025/26 tax year the standard Personal Allowance is £12,570 — so the standard code for someone with no benefits, no second job and full allowance is 1257L.

The numeric part is rounded for compactness. A PA of £12,570 produces "1257" (the last digit is dropped, not rounded). Where adjustments push the allowance off a round £10, HMRC rounds down to the nearest £10 in your favour. The letter that follows — the suffix — describes who you are: standard taxpayer, Marriage Allowance recipient, pensioner, no allowance, etc. Where a prefix letter appears instead (K, S, C, D0, D1, BR), it overrides or modifies the calculation method entirely.

Suffix letters explained

Suffix changes are common life-events. Get married and apply for Marriage Allowance — both partners' codes flip to M and N respectively. Become an additional-rate earner and lose your PA — your code shifts toward T as HMRC tapers it down. Inherit a state pension that pushes you into the system — your code reduces accordingly.

Prefix letters explained

Prefix letters replace the normal "PA-then-bands" logic with something else:

• K — negative allowance. Total deductions (benefits in kind, untaxed income) exceed your PA, so the code adds to taxable pay rather than subtracting. K475 means −£4,750. Common for senior employees with company cars, fuel, private medical and accommodation.
• S — Scottish taxpayer. S1257L is taxed under the six-band Scottish Income Tax structure (Starter 19%, Basic 20%, Intermediate 21%, Higher 42%, Advanced 45%, Top 48% for 2025/26) — not the rUK three bands.
• C — Welsh taxpayer. C1257L is currently taxed at identical rates to England, but the prefix exists so HMRC can route receipts to the Welsh Government and so Wales could vary rates in future.
• D0 — all income taxed at higher rate 40% (or Scottish Higher 42%). Used for a second job where the main job already exhausts the basic-rate band.
• D1 — all income taxed at additional rate 45% (or Scottish Top 48%). Used where the second job sits wholly above the additional-rate threshold.
• BR — Basic Rate. All income taxed at 20% (Scottish 20% basic equivalent) from the first pound. The default second-job code where the main job uses the whole PA but does not exhaust the basic-rate band.

Northern Ireland uses the same codes as England (no prefix). The S and C prefixes are determined by HMRC's residency database — usually your address — and propagate automatically when you move across the border.

Emergency tax codes (W1 / M1 / X)

W1 (weekly payroll) and M1 (monthly payroll) are non-cumulative markers appended to a code, e.g. 1257L W1. Sometimes shown as X on HMRC notices. They tell payroll: treat this pay period in isolation. Do not look back at previous pay or tax in the year.

Emergency codes are applied when payroll has insufficient information to calculate cumulative tax — no P45, no signed starter checklist, or the employee starts mid-year and HMRC has not yet issued a P6. They almost always over-deduct in the first few periods of a new job, because the period's pay is annualised as if it continued all year.

How to escape an emergency code: hand your new employer your P45 (parts 2 and 3) on day one. If you cannot — for instance, your previous job was self-employment or you were not working — complete the HMRC starter checklist with the correct statement:

• Statement A — first job since 6 April. Code: 1257L cumulative.
• Statement B — only job, but not first since 6 April. Code: 1257L W1/M1.
• Statement C — already have another job/pension. Code: BR.

HMRC reconciles emergency-coded years automatically via the P800 process between July and November after year-end and refunds any over-deduction by cheque or direct transfer.

Worked K-code example

The legal cap: a K-code can never deduct more than 50% of gross payin any single period (the "K-code limit"). If the maths would breach that, payroll caps the deduction and the under-collection rolls into a future period or year-end reconciliation. This stops high-BIK employees losing their entire wage to a single tax bill.

D0 and D1 codes — second-job higher rates

When you take a second job, HMRC must decide how to split your Personal Allowance and basic-rate band between the two payrolls. The default is to leave the main job on 1257L (full PA) and put the second job on BR (20% on everything). That works fine if your combined income stays inside the basic-rate band.

If your main job already uses up the basic-rate band (above ~£50,270 of taxable pay), every pound of second-job income should be taxed at 40% — so HMRC issues D0 on the second payroll. If your main job pushes you above £125,140 (additional-rate threshold), the second job switches to D1 at 45%.

Caveat: HMRC issues these codes based on its estimate of your annual income, which is often a year out of date. If you change jobs, get a big raise or take on a third employment, the estimate lags and your second-job code may still be BR when it should be D0. The Self Assessment return (or P800 reconciliation if you do not file one) collects any shortfall after year-end. Avoid the surprise by telling HMRC about the change via your Personal Tax Account.

Common tax-code errors and how to fix them

• Wrong code from day one — Check P60 + payslip + Personal Tax Account. Mismatches usually mean your employer did not receive HMRC's latest P9. Ask payroll to refresh from HMRC's Data Provisioning Service.
• Emergency code stuck — Provide your P45 or complete the starter checklist. If your employer already filed an FPS without P45 data, only HMRC can issue a corrective P6 — log into Personal Tax Account and confirm the right statement.
• 0T after a job change — Same root cause as emergency code. Once a cumulative code is issued mid-year, payroll refunds the over-deduction automatically through the next payslip.
• K-code shock — Read the coding notice carefully. Common drivers: a company car you forgot you had, BIKs from a previous tax year not flowing through P11D properly, or untaxed dividend/savings income HMRC is collecting via PAYE. If a listed deduction is wrong, dispute it via Personal Tax Account before more periods process.
• Two PAs in use — If your code at both jobs starts with 1257L, your PA is being double-counted. Tell HMRC immediately; the smaller job should normally be BR.
• Marriage Allowance never applied — If you transferred the allowance but never saw the M suffix appear, log into Personal Tax Account and check the application status. Claims can be backdated four tax years.
• Backdated refund — Missed in-year corrections can be claimed for up to 4 years after the end of the tax year, either via Self Assessment or by writing to HMRC.

Scotland, Wales and Northern Ireland — devolved codes

Income tax devolution is incomplete: Scotland sets its own rates and bands, Wales has the power to vary rates (but for 2025/26 has not), and Northern Ireland uses rUK rates. The PAYE code prefix reflects this:

• S = Scottish taxpayer (e.g. S1257L, SBR, SD0, SD1, SD2, SD3). Six tax bands: 19/20/21/42/45/48%.
• C = Welsh taxpayer (e.g. C1257L, CBR, CD0, CD1). Currently identical rates to England.
• (no prefix) = England or Northern Ireland. Three bands: 20/40/45%.

Historical confusion:when devolved rates first launched, some commentary used S for both Scottish and Welsh codes — this is wrong for 2025/26. Currently and consistently, S is Scottish and C is Welsh ( "C" is from the Welsh Cymru). Residency is determined by HMRC based on your main residence in the tax year, not your employer's location.

Multiple-job scenarios

Where main and second job earnings are similar, you can request HMRC to split the allowance— for example, 600L on each job — so neither overtaxes or undertaxes in isolation. This is rarely useful in practice because most people's pay across jobs is uneven, but it can smooth cashflow for two part-time roles of similar pay.

HMRC coding notices — P9X, P9T and P6

HMRC sends coding notices to both employer and employee:

• P9X — annual bulletin to employers in February/March each year, listing default code uplifts (e.g. "move all L codes by 0" if the PA is frozen).
• P9T — your individual coding notice for the new tax year, posted in February or visible in the Personal Tax Account immediately.
• P6 — mid-year change to your code, sent to the employer electronically. You see the change on your next payslip.
• P11D — annual report of taxable benefits in kind your employer provided. Drives K-code adjustments for the following year.

The Personal Tax Account (gov.uk/personal-tax-account) is the single source of truth — it shows the live code, every deduction HMRC used to build it, and lets you challenge items in minutes. If your employer's payslip shows a different code, raise it with payroll: they may be operating an older P6 that has since been superseded.

Year-end documents — P60, P45, P11D

• P60 — issued by 31 May each year. Shows your final tax code, total pay and tax deducted for the year just ended. Keep it: HMRC may ask, and it is needed for mortgage, visa and benefit applications.
• P45 — issued when you leave a job. Shows the code in force on your leaving date, plus year-to-date pay and tax. Give parts 2 and 3 to your new employer to avoid an emergency code.
• P11D — issued by 6 July if your employer provides taxable benefits not already taxed through payroll. Drives the next year's K-code or T-code adjustment.

Cross-reference the P60 code against the codes shown on every payslip in the year. Where they diverge, the latest payslip wins — but discrepancies between mid-year and year-end codes can create P800 reconciliations after year-end. Keep payslips for at least 22 months after the end of the tax year (HMRC's standard compliance window) or 6 years if you file Self Assessment.

Putting it together

Tax codes look cryptic but follow a tight logic: number × 10 = allowance, suffix tells HMRC about you, prefix tells PAYE software how to calculate. Most workers stay on 1257L for years without issue. The danger zones are new jobs (emergency codes), benefits in kind (K-codes), multiple employments (BR/D0/D1), and unsuspected mid-year notices (P6). Check your code on every payslip, log into your Personal Tax Account at least once a quarter and any time you change jobs or get a raise, and challenge anything that looks wrong before more pay periods are processed. A 30-second check now beats a 6-month P800 wait next summer.