How to Check Your Tax Code in 2026 (and Reclaim Overpaid Tax)

Quick answer

Your tax code tells your employer how much tax-free income to give you before deducting income tax. The standard 2026/27 code is 1257L, built from the £12,570 personal allowance (drop the last digit: 1257). To check yours, look at your payslip, P45, P60 or HMRC coding notice, or open your Personal Tax Account for the live version. If your code differs from 1257L and you do not know why, it is worth understanding before you quietly overpay (or underpay) for months. You can see exactly how a code translates into tax with the

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How to read your tax code

A tax code has numbers and a letter.

• The numbers are your tax-free allowance with the final digit removed. So 1257 means £12,570 of tax-free income.
• The letter describes your situation:
  • L — you get the standard personal allowance (the usual code).
  • M / N — you have received or given part of your allowance via Marriage Allowance.
  • T — your code includes other calculations HMRC reviews.
  • K — you have income that exceeds your allowances (for example, large taxable benefits), so the code adds to your taxable pay instead of subtracting.
  • BR / D0 / D1 — all your income from that source is taxed at basic (20%), higher (40%) or additional (45%) rate, common on second jobs or pensions.
  • NT — no tax to be deducted.

So 1257L is the standard, "nothing unusual" code for someone with the full personal allowance and one employment.

Where to find your tax code

You have several reliable sources:

1. Your payslip — usually printed near your National Insurance number.
2. Your P60 — the end-of-year summary your employer gives you after 5 April.
3. Your P45 — issued when you leave a job.
4. HMRC coding notice (P2) — the letter HMRC sends explaining how your code was worked out.
5. Your Personal Tax Account or the HMRC app — the live, authoritative version, including HMRC's reasoning.

The online account is the best place to check, because it shows how the code was built — for example, an allowance reduced by an estimated company car benefit or an underpayment being collected.

Step-by-step: check your code is right

1. Find your current code from your payslip or Personal Tax Account.
2. Compare it to 1257L. If it matches and you have one job and no taxable benefits, it is almost certainly correct.
3. If it is different, find the reason. Your coding notice will list the adjustments: company benefits, untaxed income, a previous underpayment, Marriage Allowance, and so on.
4. Check the adjustments are accurate. HMRC often uses estimated figures for things like a company car or medical insurance. If you no longer have that benefit, the estimate is wrong and your code is wrong.
5. Sanity-check the tax. Plug your salary and code into the
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   and compare against your actual payslip. A mismatch is a red flag.

Emergency tax codes

If your employer does not have enough information — typically when you start a job without a P45 — you may be put on an emergency code: 1257L W1, 1257L M1 or 1257L X.

These give you the standard allowance but on a non-cumulative basis, meaning each week or month is taxed in isolation rather than smoothing your allowance across the year. The effect is usually that you overpay, especially if you started partway through the year and have unused allowance from earlier months that the emergency code ignores.

The fix is to get onto a normal cumulative 1257L code, which happens automatically once HMRC receives your details (often via your new employer's first Full Payment Submission, or once you give them your P45). Any overpayment is then repaid through your wages.

Why tax codes go wrong

Common triggers for an incorrect code include:

• Starting a new job without handing over a P45.
• Having two jobs or a job and a pension, where the allowance is split or a BR/D0 code is applied to the second source.
• Company benefits such as a car, fuel or private medical insurance, which reduce your code — and where HMRC's estimates can lag reality.
• Starting or stopping a benefit like the State Pension, which is taxable but paid without tax deducted, so it is collected through your code.
• Marriage Allowance being applied or removed.
• A previous year's underpayment being clawed back through your current code.

Because the system relies on estimates and timely information, errors are genuinely common — checking once a year is sensible, and checking after any life or job change is essential.

How to reclaim overpaid tax

If you have overpaid because of a wrong code:

• During the tax year: once the correct code is applied, HMRC instructs your employer to repay the overpayment through your wages, often as a noticeable boost in the next pay packet.
• After the tax year: HMRC reconciles your PAYE records and, if you overpaid, sends a P800 calculation explaining the refund, which you can usually claim online into your bank account.
• To speed things up: update your details in your Personal Tax Account, remove incorrect benefits, or contact HMRC directly. Do not wait passively if the amounts are large.

You can normally reclaim overpaid tax going back up to four tax years, so it is worth reviewing old codes if you suspect long-running errors.

If you have underpaid

A wrong code can also mean you have underpaid, which is less pleasant. HMRC will usually collect the shortfall by adjusting your future tax code (spreading it over the next year) rather than demanding a lump sum, provided the amount is within limits. Either way, the sooner you spot it, the smaller and more manageable the correction.

A worth-checking case: Marriage Allowance

If you are married or in a civil partnership and one of you earns under the personal allowance while the other is a basic-rate taxpayer, Marriage Allowance lets the lower earner transfer £1,260 of allowance to the higher earner. This shows up as an M or N suffix on your codes. It is frequently unclaimed and can be backdated, so it is worth checking whether you qualify with the

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Second jobs and the BR code

One of the most misunderstood situations is having two jobs at once. Your personal allowance can only be used once, so HMRC usually applies it to your main job (1257L) and taxes the second job in full, often with a BR code (basic rate, 20% on everything). This is frequently correct — your allowance is already being used elsewhere — but it can be wrong in two directions:

• If your main job does not use up your full allowance, you may be overpaying on the second job, and you can ask HMRC to split your allowance across the two.
• If your combined income tips you into the higher-rate band, a BR code on the second job may undercollect, leaving you with a bill.

The same logic applies to a job alongside a pension. The key is to look at your total income across all sources and check the codes add up to the right overall tax, rather than judging each code in isolation.

What the K code means

A K code is the one that surprises people, because it works backwards. Normal codes give you tax-free allowance to subtract; a K code means your deductions (untaxed income, large benefits, or tax owed from earlier years) exceed your allowance, so the code instead adds an amount to your taxable pay. For example, K500 adds £5,000 to your taxable income for the year. K codes are common for pensioners with a State Pension larger than their remaining allowance, or for people with substantial company benefits. There is a safeguard: a K code cannot take more than 50% of your gross pay in any pay period.

Scotland and Wales

Tax codes also carry a regional prefix. Scottish taxpayers have an S prefix (for example S1257L) because Scotland sets its own income tax bands and rates. Welsh taxpayers have a C prefix (C1257L), though Welsh rates currently mirror the rest of the UK. Your prefix is set by where you live, not where you work, and getting it wrong can mean tax calculated under the wrong regime — so if you have moved across a border, check that your prefix reflects your current home address.

How often HMRC changes your code

HMRC can issue a new code at any time during the year if your circumstances change — a new benefit, a second job, a State Pension starting, or an underpayment being collected. Each change generates a coding notice. Because the system is driven by estimates and real-time payroll data, mid-year adjustments are normal and not a sign of error in themselves. What matters is that you understand why a change happened. If a new code arrives and the reason is not obvious, log in to your Personal Tax Account and read the breakdown before assuming it is right.

Annual checklist

• Once a year, compare your code to 1257L and review your HMRC coding notice.
• After any job change, confirm you are off any emergency code and onto a cumulative basis.
• After gaining or losing a benefit (car, medical insurance, State Pension), check the code reflects it accurately.
• Keep your P60 and P45s so you can prove your figures if you need a refund.

The bottom line

Checking your tax code takes a few minutes and can save (or recover) real money. In 2026/27 the standard code is 1257L; anything different deserves a quick look at your HMRC coding notice to confirm the reason is genuine. Emergency codes and outdated benefit estimates are the usual culprits behind overpayment, and HMRC will normally refund you automatically once the right code is in place. Confirm your numbers stack up with the

, and review your code whenever your job or benefits change.