Northern Ireland tax codes look the same as codes in England because Northern Ireland has no devolved income tax power. The standard code for 2026–27 is 1257L, reflecting a tax-free Personal Allowance of £12,570.1House of Commons Library. Direct Taxes: Rates and Allowances for 2026/27 The number tells your employer or pension provider how much you can earn before tax starts; the letter tells them how to apply that allowance. Get either wrong and every payslip is wrong.
Reading the Number
HMRC takes your Personal Allowance, subtracts any adjustments, and drops the last digit. Full allowance with no adjustments gives 1257.2GOV.UK. Income Tax Rates and Personal Allowances Your employer spreads that allowance evenly across your pay periods so tax comes off gradually.
The number falls if you have taxable benefits from work (a company car, private medical cover) or untaxed income like savings interest that HMRC is collecting through PAYE. It rises if you qualify for extras such as Blind Person’s Allowance. Every shift in the number changes your take-home pay directly.
No Prefix Means Northern Ireland or England
Scotland and Wales set some of their own income tax rates, so HMRC marks those taxpayers with a letter prefix: “S” for Scotland, “C” for Wales.3GOV.UK. PAYE Manual – Coding: General Principles: Scottish Income Tax / Welsh Income Tax Northern Ireland residents pay the same rates and use the same bands as England, so codes carry no regional letter. A plain 1257L is the standard England and Northern Ireland format.
The Rates Your Code Applies To
The Personal Allowance and rate thresholds are frozen in cash terms through at least 2030–31, so the 2026–27 bands are unchanged from recent years.4House of Commons Library. Fiscal Drag: An Explainer
- Up to £12,570: 0% (Personal Allowance).
- £12,571 to £50,270: 20% basic rate.
- £50,271 to £125,140: 40% higher rate.
- Over £125,140: 45% additional rate.
Some code letters lock every pound from one job or pension to a single rate, ignoring the bands.2GOV.UK. Income Tax Rates and Personal Allowances
What the Letters Mean
The letter after the number controls how HMRC treats the income from that source.5GOV.UK. Tax Codes – What Your Tax Code Means
- L: standard Personal Allowance. Most people with one job or pension see 1257L.
- BR: every pound taxed at 20%. Typical for a second job when the allowance sits with your main income.
- D0: every pound taxed at 40%. Used for a second income when your main earnings already fill the basic-rate band.
- D1: every pound taxed at 45%. Used when combined income exceeds £125,140.
- 0T: no Personal Allowance applied. Either it’s used up elsewhere or your new employer doesn’t have the details to code you properly yet. Tax starts at 20% and climbs through the bands.
- NT: no tax deducted. Applies only in a small number of specific situations.
- T: HMRC needs to review your record, or your allowance involves calculations beyond the standard amount.6GOV.UK. PAYE Manual – Coding: Codes: How They Are Used and Calculated: Suffix Codes: The Suffix
K Codes: When Deductions Exceed Your Allowance
A code that starts with “K” works differently. It means untaxed income or benefits-in-kind add up to more than your Personal Allowance, so instead of giving you a tax-free amount, the code adds taxable income to each pay period. Common causes are receiving the State Pension alongside employment income, owing tax from a previous year that HMRC is collecting through wages, or holding large company benefits.7GOV.UK. Tax Codes – If You Have a K in Your Tax Code
There is a cap. Your employer cannot deduct more than half your pre-tax pay or pension using a K code, no matter how large the K number.7GOV.UK. Tax Codes – If You Have a K in Your Tax Code Anything that can’t be collected through PAYE, HMRC will pursue separately.
Marriage Allowance: M and N
If one spouse or civil partner earns less than the Personal Allowance, the lower earner can transfer £1,260 of their allowance to the higher earner, cutting the recipient’s tax bill by up to £252 a year.8GOV.UK. Marriage Allowance Both codes change to show it: N means you’ve given some allowance away and your number sits below 1257; M means you’ve received it and your number sits above 1257. The higher earner must be a basic-rate taxpayer for Marriage Allowance to apply.5GOV.UK. Tax Codes – What Your Tax Code Means
Blind Person’s Allowance
If you are registered as severely sight impaired, you get an extra £3,250 on top of the standard Personal Allowance for 2026–27, taking the total tax-free amount to £15,820 for someone with no other adjustments. Any unused portion can be transferred to a spouse or civil partner.9GOV.UK. Blind Person’s Allowance – What You’ll Get
Emergency Codes
When HMRC lacks the information to give you a proper code, your employer runs a temporary emergency one. You’ll spot it by the ending: W1 for weekly pay, M1 for monthly, X when pay dates vary.10GOV.UK. Tax Codes – Emergency Tax Codes The usual cause is starting a new job without handing over a P45 from the previous one.
An emergency code is non-cumulative. A normal code looks at everything you’ve earned since 6 April and accounts for the allowance you’ve built up. A non-cumulative code ignores all of that and treats each pay period as if it’s the only one that exists. Unused allowance from earlier months isn’t carried forward, so the tax taken is usually higher than it should be.
To fix it, give your new employer your P45 as soon as possible. Once HMRC issues a cumulative code, the payroll system recalculates the year to date and any excess tax comes back through your next payslip. If the emergency code runs all the way to 5 April, HMRC sends a P800 calculation after the tax year ends.11GOV.UK. Tax Overpayments and Underpayments
The £100,000 Allowance Taper
If your adjusted net income tops £100,000, you lose £1 of Personal Allowance for every £2 above the threshold. By £125,140 the allowance is gone.2GOV.UK. Income Tax Rates and Personal Allowances That produces an effective 60% marginal rate between £100,000 and £125,140: the 40% higher rate plus the withdrawal of allowance. Your code number falls below 1257 to match, and at higher income levels you may see 0T or a K code instead.
Checking and Correcting a Wrong Code
Before you challenge a code, pull together what shows your real position: your P45 if you’ve recently changed jobs, your latest P60, any details of untaxed income (savings interest above the Personal Savings Allowance, rental income, dividends), and the taxable value of any benefits-in-kind your employer provides.12GOV.UK. Your P45, P60 and P11D Form
The quickest route is HMRC’s “Check your Income Tax” service, which lets you update income details and flag anything that looks wrong.13GOV.UK. Check Your Income Tax for the Current Year You can reach it through your Personal Tax Account or the HMRC app; you’ll need your National Insurance number and identity verification such as a UK passport, P60, or recent payslip.14GOV.UK. Personal Tax Account: Sign In or Set Up Phone contact is also available through HMRC’s general enquiries lines.15GOV.UK. Employers: General Enquiries
Once HMRC processes the update, they issue a coding notice (form P2) to you and instruct your employer separately. Your employer can’t change the code on their own; they use whatever HMRC tells them. HMRC aims to update you and your employer within 15 working days, and the new code takes effect from your next payday after your employer receives it.16GOV.UK. Tax Codes – If You Think Your Tax Code Is Wrong If you were underpaying, deductions go up; if you were overpaying, payroll recalculates cumulatively and refunds the difference through your wages.
Getting Back Overpaid Tax
Overpayments recover in two ways. If the code is corrected mid-year, the refund flows through payroll once the cumulative recalculation catches up. If the overpayment isn’t caught until after 5 April, HMRC sends a P800 or Simple Assessment letter setting out what’s owed.11GOV.UK. Tax Overpayments and Underpayments
You have four years from the end of the relevant tax year to claim a refund. After that, HMRC treats the year as settled.17GOV.UK. HMRC Self Assessment Claims Manual – SACM12155 – Overpayment Relief: Time Limits for Making a Claim If you think you’ve overpaid and HMRC hasn’t been in touch, don’t wait. Log in to your Personal Tax Account or use the Check your Income Tax service and start the claim yourself.