Tax Code Calculator
Your tax code is not just a random string of characters — every letter and number means something specific, and misreading it, or having the wrong one applied, genuinely changes how much tax comes out of your pay each month. This calculator decodes any UK tax code, explains exactly what it means, and estimates the tax impact on a given income.
Tax Code Calculator
Decode your PAYE tax code and check you are on the right code for 2026/27.
The Standard Code Most People Have
1257L is the standard code for 2026/27, representing the full £12,570 Personal Allowance with no adjustments — the number is always the tax-free allowance divided by ten, and the letter indicates the type of code. An M or N suffix instead of L means you are involved in the Marriage Allowance, either receiving 10% of a partner’s allowance (M) or having transferred 10% of your own away (N), which shifts the numeric part accordingly.
Checking this number against your genuinely expected Personal Allowance is a quick, useful sanity check — for most people with no specific adjustments, benefits, or previous underpayments, the numeric part should correspond closely to the standard £12,570 allowance, and a meaningfully different figure is worth investigating rather than assuming it is simply how your code has always looked.
Scottish and Welsh Codes Look Different — And That’s Correct
An S or C prefix directly attached to the rest of the code — S1257L, C1257L, and so on — identifies a Scottish or Welsh taxpayer specifically, since Income Tax is partially devolved and Scotland in particular uses a genuinely different band structure from the rest of the UK. This prefix does not change your Personal Allowance figure itself, which stays the same UK-wide, but it does signal that different tax bands and rates apply once your income is actually calculated, which is worth checking against our Income Tax Calculator‘s Scottish option for the full, accurate calculation.
This is worth being aware of specifically if you have moved between Scotland and the rest of the UK, or vice versa — your tax code prefix should update to reflect your current residency status, and an outdated prefix can mean the wrong band structure is being applied to your income.
When BR, D0 or D1 Shows Up Instead
BR, D0 and D1 codes carry no personal allowance at all — BR taxes everything at the basic 20% rate, D0 at the higher 40% rate, and D1 at the additional 45% rate, applied to the entire income from that specific source with nothing tax-free. These typically appear on a second job or pension, reflecting that your full Personal Allowance has already been allocated to your main source of income, so the second source is taxed from the very first pound. Seeing one of these on a second job is not automatically a mistake — it is often exactly correct, provided your allowance is genuinely being used in full elsewhere. Our Two Jobs Tax Calculator is useful for seeing exactly how your allowance is genuinely split, and whether a BR, D0 or D1 code on your second job is correctly reflecting that split.
Understanding a K Code Without Panicking
A K code means your untaxed income or benefits — company car benefit, or unpaid tax from a previous year, are common examples — exceed your Personal Allowance entirely, so instead of a tax-free amount being subtracted from your pay before tax, an amount is genuinely added on top of your taxable income instead. A K475 code on a £40,000 salary, for example, adds £4,750 to your taxable income, pushing your estimated tax up to roughly £10,360 for the year, compared with roughly £5,486 on the same salary under a standard 1257L code — a considerably larger deduction, but a correct and expected one given what a K code represents, not an error to be alarmed by.
Frequently Asked Questions
What should I do if my tax code looks wrong?
Contact HMRC directly through your Personal Tax Account or by phone — they can explain exactly why a specific code was issued and correct it if it is genuinely wrong, and any overpaid or underpaid tax from an incorrect code is adjusted once corrected.
Why did my tax code change partway through the year?
A tax code can change mid-year for several reasons — a change in company benefits, a new job affecting your allowance split, or HMRC correcting an earlier estimate — and your employer applies the new code as soon as they receive notification from HMRC.
Does an emergency tax code mean I am being overtaxed?
An emergency code, often shown as 1257L W1, M1 or X, applies your standard allowance but on a non-cumulative basis, which can occasionally result in slightly more tax being deducted temporarily until HMRC issues your correct, cumulative code.
Can I have different tax codes for different jobs?
Yes — your Personal Allowance is typically allocated to one job (usually your main or highest-paying one), with any additional job receiving a code such as BR, D0 or D1 that reflects no further allowance being available for that specific source.
Does 0T mean I have no personal allowance at all?
Yes, for that specific source of income — 0T is used when your full allowance has been used elsewhere, or when your employer has not yet received your details, and results in tax being calculated across the standard bands but with no tax-free amount subtracted first.
Important Information
This calculator provides an estimate based on current 2026/27 tax rates for general information purposes only and does not constitute tax advice. For confirmation of your specific tax code, contact HMRC directly. See our Disclaimer for further information.