Tax Code Calculator & Checker for 2026/27

Decode your code with the tax code calculator

Enter your tax code in the tool above and it returns your tax-free allowance, the rate it implies, and what the letters actually mean. The number is the headline: multiply it by ten and you have the rough amount of income you can earn before tax kicks in across the year. The letters tell HMRC and your employer how to treat the rest. Below you will find the full logic, worked examples with real figures, and the specific traps that catch people out.

What a tax code actually is

Your tax code is the instruction HMRC gives your employer or pension provider so the right amount of Income Tax comes out of your pay before you ever see it. It is the engine behind PAYE (Pay As You Earn). It is not a measure of how much tax you pay overall - it is a shorthand for how much of your income should be tax-free, and at what rate the rest should be taxed.

For 2026/27 the standard Personal Allowance is £12,570. Knock off the final digit and add the most common suffix and you get 1257L - the code most employees on a single job will see. The letter L simply means you are entitled to the standard tax-free Personal Allowance with no adjustments.

Because PAYE spreads your allowance evenly across the year, a monthly-paid employee on 1257L gets roughly £1,047 of tax-free pay each month (£12,570 ÷ 12), and a weekly-paid one gets about £241 (£12,570 ÷ 52). Anything above that in the period is taxed at the appropriate rate.

How to read your tax code: 1257L and beyond

Most codes follow a simple pattern: a number, then one or more letters. Here is how each part works.

The number is your tax-free allowance for the year with the last digit removed. So 1257 means £12,570; 1100 would mean £11,000; 313 would mean £3,130. The number shrinks if you have deductions (a company car, untaxed savings, or tax owed from a previous year) and can grow if you have allowable expenses or a Marriage Allowance transfer.

The most common letters mean:

• L - you get the standard tax-free Personal Allowance.
• M - you have received a Marriage Allowance transfer of 10% of your partner's allowance, so your allowance is larger.
• N - you have given away 10% of your allowance to your partner under Marriage Allowance, so yours is smaller.
• T - your code includes other calculations HMRC needs to review, often where the income-over-£100,000 allowance taper applies.
• Y - you were born before 6 April 1938 and qualify for a higher age-related allowance.

The letter sits after the number for these. A few codes work entirely differently, which the next section covers.

BR, D0, D1, 0T, NT and K codes explained

Some codes ignore the allowance idea altogether and instead set a flat rule. These are the ones that surprise people.

• BR - Basic Rate. Every pound from this source is taxed at 20%, with no tax-free allowance applied. Common on a second job or a pension where your main allowance is already used up elsewhere.
• D0 - all income from this source taxed at the higher rate, 40%.
• D1 - all income taxed at the additional rate, 45%.
• 0T - no Personal Allowance at all, with each slice taxed at the rate it falls into (20%, then 40%, then 45%). Often appears when you start a job without a P45 or your allowance has been fully used.
• NT - No Tax. Nothing is deducted from this income; rare, and usually deliberate.
• K codes - the reverse of a normal code. A K code means your deductions (such as a company car benefit or state pension) are bigger than your allowance, so instead of tax-free pay you have extra income added to your taxable pay. K475 adds £4,750 to your taxable income across the year. There is a legal safeguard: a K code can never take more than half of that period's pay in tax.

If your code starts with an S (for example S1257L) you are taxed under Scottish Income Tax rates and bands; a C prefix (C1257L) means Welsh rates apply. The Personal Allowance is the same UK-wide - £12,570 - but Scotland sets its own bands and rates, so two people on identical pay with S and standard codes can take home different amounts. If you live in Scotland, our Scotland tax calculator applies the Scottish bands in full.

How the tax code calculator works

The arithmetic behind the tool is short. In plain words:

Tax-free pay = tax code number × 10. Then taxable pay = your income − tax-free pay, and the tax is worked out by running that taxable amount through the 2026/27 bands.

For a normal suffix code (like 1257L) the calculator does this:

• Multiplies the number by ten to get your annual allowance (1257 → £12,570).
• Subtracts that allowance from your income to find taxable pay.
• Applies 20% up to the basic-rate limit of £37,700 of taxable income, 40% on taxable income from £37,700 to £125,140, and 45% above that.

For flat-rate codes the logic changes: BR applies a straight 20%, D0 a straight 40%, D1 a straight 45%, and 0T runs your full income through the bands with zero allowance. For a K code, the number is multiplied by ten and added to taxable pay rather than subtracted. The tool reflects each of these paths so the result matches what your employer's payroll would actually deduct.

One important caveat: PAYE works per pay period and is normally cumulative, meaning each payday looks at your total pay and tax so far in the year and adjusts. An annual calculator gives you the yearly picture; the exact figure on a single payslip can differ slightly because of rounding and the cumulative method. To see a full take-home breakdown including National Insurance, use the salary calculator, and for the Income Tax bands alone the income tax calculator shows the band-by-band split.

Worked example: Priya on 1257L

Priya is a primary school teacher in Leeds earning £45,000 with the standard 1257L code.

• Tax-free pay: 1257 × 10 = £12,570.
• Taxable pay: £45,000 − £12,570 = £32,430.
• All of that sits within the £37,700 basic-rate band, so it is taxed at 20%: £32,430 × 0.20 = £6,486.

So her code is correct for her salary, and PAYE should collect £6,486 in Income Tax across the year - about £540 a month. If her payslip showed a much higher deduction, the code would be the first thing to check.

Worked example: a second job on a BR code

Tom earns £28,000 in his main job (code 1257L, which uses up his whole £12,570 allowance) and takes a weekend bar job paying £6,000 with a BR code.

• Main job: £28,000 − £12,570 = £15,430 taxable at 20% = £3,086.
• Second job on BR: every pound taxed at 20% → £6,000 × 0.20 = £1,200.

Because Tom's combined income (£34,000) is still inside the basic-rate band, the BR code happens to be exactly right - he would owe 20% on the second job anyway. BR only over-taxes you when part of your second income should have been tax-free, which is why the code, not the rate, is what you check. If you suspect you have been overcharged because of an emergency code on starting a job, the emergency tax calculator works through exactly how much that costs and how to get it back.

Worked example: a K code with a company car

Sandra, a sales manager, has a company car taxed at a £7,820 benefit and a small amount of untaxed savings interest, giving total deductions of £17,320 against her £12,570 allowance. HMRC issues a K475 code.

• Deductions exceed allowance by £17,320 − £12,570 = £4,750.
• The K475 adds £4,750 to her taxable pay across the year, so on a £50,000 salary she is taxed as if she earned £54,750.

A K code is not a mistake - it is the system clawing back tax on benefits through your salary. But it is worth confirming the benefit figures are right, because an out-of-date company car value can inflate the code.

2026/27 rates & thresholds (England, Wales & Northern Ireland)

These are the figures the calculator applies to a standard tax code for 2026/27. Scotland uses different bands.

Source: gov.uk - tax codes, checked for the 2026/27 tax year.

How to check your tax code is right

Three quick checks catch most errors. First, does the number match your circumstances? If you have one job, no taxable benefits and no Marriage Allowance, 1257L is what you would normally expect. Second, do you have a flat-rate code (BR, D0, 0T) on income that should be getting some allowance? That is the classic sign your allowance has not been applied to the right source. Third, has anything changed mid-year - a new job, a company car ending, a second income stopping - without your code updating to match?

You can see your current code and how HMRC built it in your Personal Tax Account on gov.uk, on your payslip, P45 or P60, or on a coding notice (form P2) that HMRC posts when it changes your code. If the figures behind it look wrong - a benefit you no longer have, or income you do not receive - you can ask HMRC to correct it.

Common mistakes and what to watch

• Assuming a higher number means you pay less tax. A bigger allowance helps, but if it is bigger because HMRC has the wrong information, you may underpay now and face a bill later.
• Ignoring an emergency code. Codes ending in W1, M1 or X are "non-cumulative" - they tax each period in isolation and often over-deduct. They usually settle once HMRC has your full details, but if they do not, you may be due a refund.
• The £100,000 trap. Once income passes £100,000 your Personal Allowance falls by £1 for every £2 over, vanishing entirely at £125,140. Your code should drop to reflect this; if it does not, you build up an underpayment.
• Two codes that do not add up. With more than one job or pension, your allowance is split or assigned to one source. If both sources apply an allowance, you will underpay; if neither does, you over-pay.
• Forgetting Scotland and Wales prefixes. An S or C code is not an error - it tells payroll which nation's rates to use. A missing prefix for a Scottish taxpayer can mean the wrong bands are applied.
• Stale benefit figures in a K code. Company car or medical benefit values that are out of date can inflate a K code and over-tax you all year.

If a check suggests HMRC has taken too much, the tax refund calculator estimates what you could be owed and points you to the right reclaim route.

These figures are estimates for guidance only and are not personal tax or financial advice. Always confirm your own code with HMRC before acting on it.

Who should use this calculator

Works out what tax code your circumstances should produce, which is the reverse of reading the code you have been given. Useful when your code has changed and you want to know whether the new one is right before accepting it.

The number is broadly your tax-free allowance divided by ten, adjusted for anything that increases or reduces it — benefits in kind, an underpayment being collected, Marriage Allowance, or a second employment. If your calculated code and your actual code differ significantly, something in HMRC’s record about you is out of date.

What this calculator assumes

• The numeric part reflects your tax-free allowance divided by ten.
• Benefits and adjustments reduce the allowance; Marriage Allowance can increase it.
• Letters denote circumstances — L standard, BR and D0 for other employments, K for negative allowances.
• S and C prefixes apply to Scottish and Welsh taxpayers.

Limitations — what it does not cover

• HMRC’s actual record, which drives the code issued — your Personal Tax Account shows the adjustments behind it.
• Estimated benefits, where HMRC uses last year’s figures until updated.
• Tax owed from a previous year, which HMRC recovers by lowering the code.
• Allowance allocation across multiple employments, changeable on request.
• Timing — a corrected code takes a pay period or two to apply.
• In-year adjustments when circumstances change.

Related calculators

Pair this with the income tax calculator to see the band-by-band tax behind your code, the salary calculator for a full take-home figure including National Insurance, and the emergency tax calculator if you have been put on a temporary code after starting a job.

You might also need

• Tax Code Checker, find out if your code is actually wrong and what to do.
• Tax Rebate Checker, check if a wrong code left you owed money.

Related tools

• Work expense tax rebate calculator, claim job expense relief.
• HMRC letter decoder, decode a coding notice.