Your tax code is the short string of letters and numbers printed on every payslip — something like 1257L, BR or 0T. Most people glance at it and move on. But your tax code directly controls how much Income Tax your employer deducts from your pay each month, and if it is wrong, you could be quietly overpaying — sometimes by more than £200 per month.

This guide explains what every common UK tax code means, how they are constructed, and what to do if yours does not look right.

💡 Quick Answer: What Does 1257L Mean?

1257L is the standard UK tax code for 2026/27. It means you are entitled to the full Personal Allowance of £12,570 — the amount you can earn each year before any Income Tax is deducted. The number 1257 is your annual tax-free allowance divided by 10. The letter L means you receive the standard Personal Allowance with no special adjustments. If your payslip shows 1257L and you have one job with no company benefits, your tax code is almost certainly correct.

In this guide

1. Why Your Tax Code Matters

In the UK, most employees pay Income Tax through PAYE (Pay As You Earn). Under PAYE, your employer deducts tax from your salary before you receive it and pays it directly to HMRC on your behalf. Your tax code is the instruction HMRC sends to your employer to tell them exactly how much of your income is tax-free and at what rate the rest should be taxed.

Get the right code and the right amount of tax is collected across the year. Get the wrong code and one of two things happens:

  • Too much tax deducted — you overpay throughout the year and either receive a refund at year end or need to claim one back from HMRC.
  • Too little tax deducted — HMRC may adjust a future tax code to collect the shortfall, or issue a P800 bill.

⚠️ Millions of people are on wrong tax codes

HMRC estimates that a significant number of UK workers are on incorrect tax codes at any given time — often without realising. Overpaying by even £50 per month costs you £600 across a full tax year. The good news is that checking your code takes about two minutes, and any overpayment is refundable.

2. How to Read a UK Tax Code: Numbers and Letters

Most UK tax codes follow a simple two-part format: a number followed by a letter.

The number: your tax-free allowance ÷ 10

The number in your tax code represents your annual tax-free income divided by 10. HMRC drops the final zero as a shorthand. To find your actual tax-free allowance, simply multiply the number by 10.

Tax Code Number Tax-Free Allowance Notes
1257 £12,570 Standard Personal Allowance 2026/27
1383 £13,830 Higher than standard — e.g. Marriage Allowance received
1131 £11,310 Lower than standard — e.g. small benefit-in-kind adjustment
500 £5,000 Reduced allowance — significant benefits or collecting underpaid tax

Your employer takes the number, multiplies it by 10 to get your annual allowance, then divides by 12 (monthly pay) or 52 (weekly pay) to apply it evenly across each pay period.

🔎 Example

Tax code 1257L gives a monthly tax-free amount of £12,570 ÷ 12 = £1,047.50. If you earn £2,500 in a month, only £1,452.50 (£2,500 − £1,047.50) is taxable. At 20%, that is £290.50 income tax for that month.

The letter: which rules apply

The letter after the number tells your employer which set of rules to use. It does not change the amount of tax-free income (that is set by the number), but it changes how the allowance is applied and at what rates income above it is taxed.

3. Tax Code 1257L Explained in Full

1257L is the most common UK tax code and has been the standard since April 2021, when the Personal Allowance rose to £12,570. The allowance has been frozen at this level since then, and is confirmed to remain at £12,570 until at least April 2028 — so 1257L will remain the standard code for the foreseeable future.

Here is exactly what 1257L means in practice for 2026/27:

What It Tells Your Employer Detail
Annual tax-free amount £12,570 (1257 × 10)
Monthly tax-free amount £1,047.50 (£12,570 ÷ 12)
Weekly tax-free amount £241.73 (£12,570 ÷ 52)
Calculation method Cumulative — based on year-to-date earnings
Who it applies to Employees with one job, no company benefits, standard circumstances

The key phrase is cumulative. With a standard 1257L code, your employer calculates tax based on your total earnings since the start of the tax year (6 April), not just your pay in the current period. This means that if you took unpaid leave or had a low-pay month earlier in the year, the system naturally adjusts later — giving you more tax-free credit and lower tax deductions to compensate.

4. Every Common UK Tax Code: Quick-Reference Table

Below is a full reference of the tax codes you are most likely to encounter on a UK payslip in 2026/27.

Tax Code Meaning Personal Allowance Applied? Typical Situation
1257L Standard Personal Allowance of £12,570; cumulative PAYE Yes — full £12,570 One job; no company benefits; standard circumstances
S1257L Same as 1257L but Scottish Income Tax rates apply Yes — full £12,570 Employee lives in Scotland
C1257L Same as 1257L but Welsh Income Tax rates apply Yes — full £12,570 Employee lives in Wales
1257L W1 Standard allowance but non-cumulative — weekly basis Yes — per week only (£241.73/week) Emergency code; new employer awaiting HMRC confirmation
1257L M1 Standard allowance but non-cumulative — monthly basis Yes — per month only (£1,047.50/month) Emergency code; new employer awaiting HMRC confirmation
BR All income taxed at basic rate (20%); no Personal Allowance No Second job where allowance is used elsewhere; or missing P45
D0 All income taxed at higher rate (40%); no Personal Allowance No Second income where total earnings exceed £50,270
D1 All income taxed at additional rate (45%); no Personal Allowance No Second income where total earnings exceed £125,140
0T No Personal Allowance; progressive rates apply from first pound No Emergency — missing starter information; or income above £125,140
K (e.g. K475) Negative allowance — extra income added to taxable pay (K number × 10) No — extra amount added instead Company car; benefits-in-kind; underpaid tax; State Pension excess
NT No Tax — employer deducts no Income Tax at all N/A Non-UK residents; tax collected via Self Assessment; specific exemptions
M Marriage Allowance received — extra 10% allowance from partner (£1,260) Yes — £13,830 Non-taxpaying spouse/partner has transferred part of their allowance
N Marriage Allowance transferred — reduced allowance by £1,260 Yes — £11,310 Transferring allowance to spouse/civil partner
T Temporary code — HMRC needs to review circumstances before issuing final code Yes — varies Complex situations; pending review

5. What Each Tax Code Letter Means

Some codes have no number at all — BR, D0, D1, NT, 0T — because the rule does not depend on an allowance. Others use a prefix (S for Scotland, C for Wales) or a suffix (W1, M1) to modify how the code works. Here is what each element does:

Letter / Prefix / Suffix What It Means
L Standard Personal Allowance — the most common letter
M Marriage Allowance: received an extra £1,260 from partner
N Marriage Allowance: transferred £1,260 to partner
T Temporary — under review by HMRC
BR Basic Rate tax on all income; zero allowance
D0 Higher Rate (40%) on all income; zero allowance
D1 Additional Rate (45%) on all income; zero allowance
K Negative allowance — the K number × 10 is added to taxable income
NT No Tax — no Income Tax deducted at all
0T Zero allowance; progressive rates from the first pound
S (prefix) Scottish taxpayer — Scottish Income Tax rates apply
C (prefix) Welsh taxpayer — Welsh Income Tax rates apply (same as England for 2026/27)
W1 (suffix) Non-cumulative, weekly basis — emergency
M1 (suffix) Non-cumulative, monthly basis — emergency
X (suffix) Non-cumulative, non-standard pay period — emergency

6. Emergency Tax Codes: W1, M1 and 0T

An emergency tax code is used when HMRC has not confirmed what allowances you are entitled to — usually because you are new to a job and your employer has not yet received your details from HMRC.

Why emergency codes happen

  • You started a new job without providing a P45 from your previous employer
  • You returned to work after a gap in employment
  • HMRC has not yet processed your starter information
  • You have recently become self-employed and then taken employment

1257L W1 and 1257L M1: the non-cumulative versions

These codes look almost identical to the standard 1257L — but the W1 or M1 suffix makes a critical difference. The W1/M1 suffix makes the code non-cumulative, meaning each pay period is calculated in isolation. Your employer does not look at your year-to-date earnings; they simply give you one period's worth of allowance (£1,047.50/month or £241.73/week) and tax everything above that.

📌 Why W1/M1 can cost you money

Imagine you start a new job in November — month 8 of the tax year — having had no employment income since April. On a cumulative 1257L code, HMRC would recognise that you have 8 months of unused allowance (8 × £1,047.50 = £8,380) and your first payslip could have zero Income Tax — even on a £2,500 monthly salary.

On a 1257L M1 emergency code, that credit is ignored. You only get one month's allowance (£1,047.50), and you pay 20% on the rest. On a £2,500 salary that is £290.50 in tax — money you do not owe. It will eventually be refunded, but only once HMRC corrects the code.

0T: no allowance at all

The 0T code is more severe. No Personal Allowance is applied — every pound you earn is taxed from the first penny using progressive rates. On a £2,500/month salary, 0T results in £500 Income Tax (20% on the full amount), compared to £290.50 on a standard 1257L code. That is an extra £209.50 per month deducted unnecessarily.

For higher earners, 0T can result in significantly larger overpayments because it applies both the 20% and 40% bands without any tax-free income being carved out.

7. The BR Tax Code

BR stands for Basic Rate. It means every pound from that employment is taxed at 20% — with no Personal Allowance applied.

When BR is correct

BR is correct and expected on a second job. Your Personal Allowance can only be applied to one income source at a time. Your main job uses the full 1257L code; your second job therefore has no allowance remaining, so BR is applied. This is how HMRC ensures the right total tax is collected across both employments.

When BR is a problem

If BR is showing on your only or main job, it almost certainly means an error has occurred. Either your P45 was not submitted, your employer did not receive your starter checklist details, or there was a payroll processing issue. In this situation you are overpaying tax and should act promptly.

🔎 How much does BR cost a basic-rate taxpayer?

On any salary within the basic-rate band, using BR instead of 1257L costs exactly the same amount — because BR removes the Personal Allowance of £12,570. At 20%, that is £12,570 × 20% = £2,514 per year, or £209.50 per month in extra tax. Whatever your salary, if BR is on your only job, you are overpaying by approximately £209.50/month compared to what you should pay on a standard 1257L code.

8. The 0T Tax Code

0T means no Personal Allowance is applied, and income is taxed using the full progressive rate bands from the very first pound:

  • 20% on the first £37,700
  • 40% on income between £37,701 and £125,140
  • 45% on income above £125,140

For most employees with typical salaries, 0T produces the same result as BR at the basic rate — but for higher earners it is significantly worse, because 0T will apply the 40% band once earnings exceed £37,700 in the year.

When 0T appears

  • A new employer has no starter information at all
  • A P45 was not provided and no starter checklist was completed
  • Your adjusted net income has genuinely exceeded £125,140 (full allowance withdrawal)
  • As an emergency measure while HMRC processes a late code update

⚠️ 0T is the most costly emergency code

For a basic-rate taxpayer, 0T is equivalent to BR (both remove the Personal Allowance). For anyone earning above £37,700, 0T is considerably worse than BR because progressive higher-rate tax applies earlier. If you see 0T on your payslip and you are not in the exceptional circumstances above, contact HMRC immediately.

9. The K Code: When Benefits Exceed Your Allowance

A K code works in reverse to a normal tax code. Instead of sheltering income from tax, the K number multiplied by 10 is added to your taxable pay each period. This happens when you have untaxed income or taxable perks whose value exceeds your Personal Allowance.

Common reasons for a K code

  • Company car — the Benefit in Kind (BiK) value can be large
  • Private medical insurance provided by your employer
  • State Pension income that is not taxed at source
  • Underpaid tax from a previous year being collected gradually
  • Living accommodation provided by an employer

🔎 K code example

You have a company car with a BiK value of £6,000 per year. HMRC reduces your standard allowance of £12,570 by £6,000 to £6,570 — but that is not a K code yet. A K code occurs when the untaxed income exceeds your allowance. For example, if you owe £15,000 in benefits against an allowance of £12,570, the excess is £2,430. HMRC would issue code K243, meaning £2,430 is added to your taxable income each year on top of your gross salary.

K codes are legitimate and not inherently a sign of an error — but they are worth checking. If you do not have company benefits, a State Pension or underpaid tax, and a K code has appeared, contact HMRC.

10. Scottish (S) and Welsh (C) Prefix Codes

If you live in Scotland, your tax code will include an S prefix — for example, S1257L. This tells your employer to apply Scottish Income Tax rates instead of the standard England/Wales rates.

Scotland has six income tax bands in 2026/27, with rates ranging from 19% (Starter) to 48% (Top), which differ significantly from the rest of the UK above approximately £30,000 gross salary. Using an England-based calculator if you live in Scotland will give you an incorrect estimate. See the Scotland tax rates 2026/27 article for a full breakdown.

If you live in Wales, your code includes a C prefix — for example, C1257L. Wales Income Tax rates are the same as England for 2026/27, so the practical impact on your take-home is currently identical to a standard 1257L code. See the Wales tax rates 2026/27 guide for more detail.

📌 Check your prefix

Your residency determines your prefix, not where you work. If you live in Scotland but work in England, your code should still carry the S prefix. If the wrong prefix is showing, your take-home may be calculated incorrectly. Verify via your Personal Tax Account on GOV.UK.

11. How a Wrong Tax Code Affects Your Monthly Pay

To make this tangible, here is how different tax codes affect monthly take-home on a £30,000 annual salary (England, 2026/27):

Tax Code Monthly Income Tax Monthly Take-Home (approx)* Difference vs Correct 1257L
1257L (correct) £290.50 ~£2,093 —
1257L M1 (emergency) £290.50 ~£2,093 Same — but may differ if mid-year start
BR (no allowance, 20% all) £500.00 ~£1,884 −£209/month
0T (no allowance, progressive) £500.00 ~£1,884 −£209/month

*Approximate figures. NI deductions are the same regardless of tax code. For an exact figure, use the take-home pay calculator with your specific tax code entered.

Being on the wrong code for a full year on a £30,000 salary could mean overpaying up to £2,514 in Income Tax. HMRC will typically refund this at year end via a P800 letter, or it will be corrected through your payroll once the code is updated — but you have to act to trigger the correction.

12. Real Scenarios: Why Tax Codes Go Wrong

Scenario 1: Starting a new job without a P45

Your P45 is issued by your old employer when you leave. If you do not provide it to your new employer promptly (or if you have not had a job before), your employer cannot confirm your tax history to HMRC. They typically apply the 1257L M1 or 0T emergency code until HMRC issues a formal code. You may overpay in early months, but this is usually corrected within one to three payroll cycles once HMRC processes your details.

Scenario 2: Second job or freelance income

If you take on a second job, your Personal Allowance is allocated to your main employment only. Your second employer will receive a BR or D0 code. This is correct behaviour — but if you believe too much tax is being deducted overall (for example, because your main job already uses only part of the basic-rate band), you can ask HMRC to split your Personal Allowance between employers. This requires contacting HMRC directly.

Scenario 3: Company car or private medical insurance

Employer-provided benefits have a taxable value set by HMRC each year. Your tax code is adjusted to collect the additional tax due — typically by reducing your tax-free number (e.g. 1257L becomes 982L) or, for larger benefits, issuing a K code. If a new benefit has started and your code has not been updated, check that HMRC has been notified of the benefit via a P11D or payrolling of benefits.

Scenario 4: Starting to receive State Pension

State Pension is taxable income, but it is paid without any tax deducted at source. HMRC collects the tax by reducing your employment tax code. For example, if your State Pension is £11,973 per year, most of your Personal Allowance is used against it, leaving very little for your employment income. The resulting code may be a low number or a K code depending on the amounts involved.

Scenario 5: Underpaid tax from a previous year

If HMRC determines you underpaid tax in a previous year (typically identified after a P800 reconciliation), they may spread the collection across a future tax year by reducing your tax code. For example, £1,200 of underpaid tax would reduce your code by 120 — so 1257L might become 1137L. Your monthly pay drops slightly as a result, but you are paying off a genuine past liability rather than being overtaxed in error.

Scenario 6: Pension income alongside employment

If you receive both a workplace or private pension and employment income, HMRC allocates your Personal Allowance to one source and applies codes like BR or D0 to the other. The split depends on the size of each income. If the allocation looks wrong, use your Personal Tax Account to adjust it.

13. Warning Signs Your Tax Code Is Incorrect

Check your current tax code against this list of warning signs:

  • 🚨 Your payslip shows BR, 0T or D0 and this is your only job
  • 🚨 Your tax code number is lower than 1257 and you have no company benefits or underpaid tax
  • 🚨 You see W1 or M1 on your code more than two or three months after starting a new job
  • 🚨 You recently started a job and your first payslip shows no tax code at all
  • 🚨 You received a PAYE Coding Notice (P2) from HMRC with an unexpected change
  • 🚨 Your take-home is significantly lower than the take-home pay calculator estimates for your salary
  • 🚨 You have an S or C prefix but do not live in Scotland or Wales
  • 🚨 You received a P800 letter showing tax underpaid — a signal to check future codes
  • 🚨 You have a K code but have no company benefits, no pension income and no underpaid tax

14. How to Check Your Tax Code

Before contacting HMRC, gather the following information:

  1. Find your current tax code. Check your most recent payslip. It is usually shown near the top, alongside your name and NI number. It will look like 1257L, 1257L M1, BR, K475, etc.
  2. Check whether it matches your situation. Use the tables in this article to understand what your code means. One job, no benefits, standard circumstances → should be 1257L. Scotland resident → should have S prefix. Second job → BR or D0 is expected.
  3. Log into your Personal Tax Account. Visit gov.uk/personal-tax-account to view your current code, see why it was set, and update any details (such as company benefits or employment changes) that HMRC may be missing. This is the fastest route to a correction without a phone call.
  4. Contact HMRC if needed. If your code still looks wrong after reviewing your account, call HMRC's Income Tax helpline on 0300 200 3300. Have your National Insurance number and employer PAYE reference to hand. Only HMRC can issue a new code — your employer cannot change it on their own.
  5. Expect a P2 Coding Notice. When HMRC updates your code, they send a PAYE Coding Notice (P2) by letter or through your Personal Tax Account. Check this carefully to understand why the change was made.

🔎 Overpaid tax? Here is what happens

If HMRC confirms you have been overpaying, the refund is usually applied through your payroll once the correct code is issued — your employer will deduct less tax in subsequent months until the balance is cleared. If the overpayment is large, or the tax year has ended, HMRC may issue a P800 and arrange a refund directly. You can also claim directly via GOV.UK if you believe you are owed a refund after the tax year ends.

15. Use a Salary Calculator to Check Your Net Pay

The quickest way to check whether your take-home looks right for your tax code is to run your salary through a calculator with the correct settings.

The take-home pay calculator lets you enter your gross salary and select your tax code, so you can compare the estimated net pay against your actual payslip. If there is a significant gap, your tax code is likely the reason.

Key calculators for each nation:

💡 How tax code affects the calculator

Entering a non-standard code — such as 1000L, K475 or BR — changes the calculator's tax-free allowance assumption and therefore the net pay estimate. If your payslip shows a lower amount than the calculator's output on a standard 1257L, the difference is likely your actual tax code. For more background on how rates are calculated, see the UK tax rates 2026/27 guide or the Northern Ireland tax rates guide.

16. Frequently Asked Questions

What does tax code 1257L mean?

1257L is the standard PAYE tax code for 2026/27. The number 1257 represents your Personal Allowance of £12,570 divided by 10. The letter L confirms you receive the standard full allowance with no special circumstances. Most UK employees with one job and no company benefits will be on 1257L.

What is an emergency tax code?

An emergency code is applied when your employer does not have enough information to confirm your correct code. The most common are 1257L W1, 1257L M1 and 0T. They are non-cumulative — each pay period is taxed in isolation — which can lead to overpaying, especially if you start a new job part-way through the tax year. Emergency codes usually resolve within a few months; if they do not, contact HMRC.

What does BR mean on my payslip?

BR means all of your income from that employment is taxed at the 20% basic rate with no Personal Allowance. It is correct for a second job (where your allowance is already used elsewhere) but should not appear on your main or only employment. If it does, you are overpaying by approximately £209.50 per month and should contact HMRC to get a corrected code.

What does tax code 0T mean?

0T means no Personal Allowance is applied and every pound is taxed using progressive rates from the first penny. It usually appears when a new employer has no starter information, or when income exceeds £125,140 (where the Personal Allowance is fully withdrawn). If 0T is appearing incorrectly, you may be overpaying significantly — contact HMRC via GOV.UK to resolve it.

What does a K code mean?

A K code means you have untaxed income — from company benefits, a State Pension, or underpaid tax — that exceeds your Personal Allowance. The K number multiplied by 10 is added to your taxable pay each period rather than removed. K codes are legitimate in the right circumstances, but should be checked if you do not have obvious taxable benefits or prior underpayments.

Why has my tax code changed?

HMRC updates tax codes when your circumstances change. Common reasons include: starting a new job, a new company benefit, beginning to receive a State Pension, underpaid tax from a previous year being collected, or changes to the Marriage Allowance. You should receive a PAYE Coding Notice (P2) whenever your code changes. If the new code looks wrong, review it via your Personal Tax Account on GOV.UK and query it with HMRC if needed.

Can I have different tax codes for different jobs?

Yes, and this is normal. Your main job receives your full Personal Allowance (typically 1257L). A second job or pension income receives a code with no allowance — usually BR, D0 or D1, depending on your total income. You can ask HMRC to split your allowance between employers if the default allocation results in overpaying, but this requires direct contact with HMRC.

What is the difference between W1 and M1 tax codes?

Both W1 (Week 1) and M1 (Month 1) are suffixes that make a tax code non-cumulative. W1 is used when you are paid weekly; M1 when paid monthly. The key difference from a standard 1257L is that year-to-date earnings are ignored — each period is treated independently. This can cause overpayment if you start a job mid-year and have unused allowance from earlier in the tax year.

What should I do if my tax code looks wrong?

First, check your Personal Tax Account at GOV.UK — you can view your current code and update employment and benefit details directly online. If the issue is not resolved there, call HMRC on 0300 200 3300. Your employer cannot change your code without HMRC's instruction. If you have been overpaying, any refund is typically applied through future payroll deductions or issued directly by HMRC via a P800. The content on this page is for general information only; for advice specific to your circumstances, contact HMRC or a qualified tax adviser.

How do I check if my take-home pay is correct for my tax code?

The fastest way is to run your gross salary through the take-home pay calculator with the same tax code that appears on your payslip. If the estimated net pay is significantly higher than what you are actually receiving, the difference is likely caused by your tax code or an additional deduction (such as pension or student loan). Compare the calculator's deductions breakdown against your payslip line by line.

17. Summary

Your tax code is a short instruction from HMRC to your employer. For the majority of UK employees in 2026/27, the correct code is 1257L — meaning a tax-free Personal Allowance of £12,570 per year, applied cumulatively across the tax year.

Other codes — BR, 0T, D0, D1, K, W1/M1 — all have specific meanings and can legitimately appear in the right circumstances. The problem arises when a code is applied incorrectly, most often after starting a new job without a P45, or when HMRC has incomplete information about your employment.

If your payslip shows a code you do not recognise, or your take-home is noticeably lower than expected, it takes only a few minutes to check your code via your Personal Tax Account on GOV.UK. Millions of UK workers overpay tax each year due to incorrect codes — and all of it is refundable once corrected.

Use the take-home pay calculator to check whether your estimated net pay matches your actual payslip. For Scotland, use the Scotland take-home pay calculator.

This article is for general information only and does not constitute personal tax advice. For advice specific to your circumstances, contact HMRC or consult a qualified tax adviser. Tax rules and codes can change — always verify current information at GOV.UK.