A quick, practical guide to checking your 2026 tax code in three places, spotting a wrong one, and getting it fixed before it costs you money.
If your April or May payslip looked a little different and you couldn’t quite say why, your tax code is the first thing to check. It’s a short string of numbers and a letter, something like 1257L or 1185L or BR, and it quietly decides how much of your pay HMRC lets you keep before income tax kicks in.
Most people never look at it. That’s usually fine, because most codes are correct. But April is when HMRC reissues codes for the new tax year, and from 2026 most of those updates arrive digitally rather than as a letter. So a lot of people are walking around on a code that changed without them noticing. Here’s how to check yours, in about ten minutes, and what to do if it’s wrong.
Your tax code tells your employer how much tax-free pay you’re entitled to this year, and the standard one, 1257L, means the first £12,570 you earn is free of income tax.
That £12,570 is the personal allowance, and it’s frozen for the 2026/27 tax year (it hasn’t moved since April 2022). The 1257 is just that allowance with the last digit dropped. The letter on the end describes your situation: L for the standard allowance, BR if all your pay from that job is taxed at the basic rate, M or N for Marriage Allowance, K if you’ve got a negative allowance because of untaxed income or benefits. Get the code wrong and every payslip for the rest of the year is wrong too, which is exactly why a ten-minute check is worth it.
You don’t need to phone anyone to find your code. It’s already sitting in at least three places.
Your payslip. Look near your name or your National Insurance number, most payroll systems print the code every period. This is the code your employer is actually using to tax you right now, which matters, because it isn’t always the code HMRC intended.
The HMRC app. This is the one I’d check first. It’s free on iOS and Android, you log in with your Government Gateway ID, and your current code is on the front screen along with a plain-English note on what it means and when it last changed. The same information lives in your online Personal Tax Account at gov.uk/check-income-tax-current-year if you’d rather use a browser.
Your P60. The document you should have received by 31 May for the tax year that just ended. It shows the code you were on at the end of that year, useful as a reference point, though it won’t reflect a change made since April.
The key thing is that these can disagree. The HMRC app shows the code HMRC has issued. Your payslip shows the code your employer’s payroll is running with. When a new code is issued and your employer hasn’t picked it up yet, the two drift apart, and that gap is where most quiet overpayments hide.
For a standard PAYE worker with one job, no company car, and no debts to HMRC, the correct code is almost always 1257L. If that’s you and that’s what you see, you’re done.
Where it gets worth checking is when the code is something else. The cost of getting it wrong is real. Take a retail worker on £12.50 an hour, 37.5 hours a week, roughly £24,375 a year. On the correct 1257L code, only the pay above £12,570 is taxed, so the income tax bill is about £2,361 a year, or around £197 a month. Now suppose payroll has them on BR by mistake, that taxes the whole lot at 20%, with no tax-free allowance at all. The bill jumps to £4,875 a year, about £406 a month. That’s roughly £209 a month of your own money sitting with HMRC until someone notices.
BR is correct on a genuine second job, where your main job is already using up the personal allowance. It’s wrong when it lands on your only job, which happens most often when you start somewhere new and your P45 hasn’t caught up.
A few other codes that should make you look twice:
1257L W1 or 1257L M1, an emergency, non-cumulative code. Payroll treats every pay period as if it’s the first of the year, so you often overpay in the early months of a new job. HMRC usually reconciles this automatically, but if you’re still on it three months in, it’s worth a prompt.1185L or 974L), HMRC has reduced your allowance, normally to collect tax owed from a previous year or to account for a taxable benefit.K code (like K475), your benefits or untaxed income are bigger than your allowance, so instead of tax-free pay you have an extra amount added to your taxable pay. K codes are correct for some people, but if you’ve got one and don’t know why, find out.If you’re not sure what your code should be in the first place, our guide to tax code 1257L walks through the standard case, and BR codes apply to second jobs.
Once you suspect something’s off, the fix depends on where the error is.
If your payslip and the HMRC app show different codes, the problem is on your employer’s side, their payroll is running on stale data. Ring or email your payroll team, tell them the code HMRC is showing, and ask them to apply it. They can’t simply use whatever code you ask for, but they can and should pick up the latest one HMRC has issued.
If the HMRC app itself shows a code you can’t explain, you’ve only got one job, no benefits, no known debt, then the issue is with HMRC’s record. Call them on 0300 200 3300 with your National Insurance number to hand. Explain why you think the code is wrong, and they’ll review it. If they agree, they’ll issue a corrected code to your employer, usually within days.
Here’s the reassuring part: a wrong code doesn’t lose you money permanently. If you’ve overpaid because of it, the correction triggers a refund, sometimes through your next few payslips, sometimes as a lump sum after the tax year ends. If you’ve underpaid, the sooner you fix it the smaller the eventual bill, because HMRC will otherwise claw it back through next year’s code.
What didn’t change: the maths. The personal allowance is still £12,570, the basic rate is still 20%, and the higher-rate threshold is still £50,270 for 2026/27. So 1257L remains the standard code for most people.
What did change is how you hear about a new code. HMRC has moved most P2 notices, the “your tax code has changed” message, to digital. Instead of a letter through the door, the update appears in your HMRC online account, with at most an email or push notification nudging you to look. It’s tidier, but it’s also easier to miss, which is the single biggest reason people have a changed code in 2026 without realising.
Two changes worth knowing about specifically:
N suffix (1131N), and the person who received it gets an M (1383M). If you see M or N and never claimed it, query it.1257L (£12,570 free) is standard for one job, no benefits, no debts.If you want to see what your take-home should actually be on your current code, at your hourly rate or salary, after tax, National Insurance, pension, and student loan, the NetPay apps do the sums for you, so you can spot a wrong code the moment your payslip doesn’t match.
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The fastest way is the free HMRC app, log in with your Government Gateway ID and your current code is on the front screen. You can also find it on any payslip, in your online Personal Tax Account at gov.uk, or on your latest P60. If your payslip and HMRC disagree, trust HMRC and ask your employer to update.
Four places: the top of your payslip (usually near your National Insurance number), the HMRC app, your Personal Tax Account at gov.uk, and your P60. The HMRC app and Personal Tax Account are the most reliable because they show the code HMRC has actually issued, not what your employer's payroll happens to be using.
First work out whether the error is on HMRC's side or your employer's. If your payslip and the HMRC app show different codes, your employer is using stale data, ring payroll and ask them to apply the latest code. If the HMRC app itself shows a code you can't explain, call HMRC on 0300 200 3300 and they'll review it. Overpaid tax from a wrong code is refunded once it's corrected.
April is when HMRC issues most new tax codes for the year, and from 2026 most of those notices are digital rather than posted. So a lot of people saw their code change without a letter arriving. Common reasons include a benefit in kind being added, an underpayment from a previous year being collected, or a Marriage Allowance claim. Check the HMRC app for the P2 notice that explains the change.
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A note on financial advice: NetPay UK calculates take-home pay based on official HMRC tax rules. This article reflects rules in force at the time of publication (1 June 2026). Tax rules change. For complex situations, consult a qualified UK accountant or visit gov.uk/income-tax.
