Tax Code T Explained

A T at the end of your tax code (for example 1257T) means your code includes other calculations to work out your Personal Allowance, per GOV.UK. The number still shows your tax-free amount – 1257T gives £12,570 – but HMRC has flagged that it needs to review your code rather than updating it automatically.

Tax-free allowance implied by this code: £12,570 a year (£1,047.50 a month).

How your pay is taxed on T

Tax is calculated exactly as for an L code with the same number. Example (England, 1257T, £30,000): £2,500 − £1,047.50 tax-free = £1,452.50 × 20% = about £290.50 a month. The T doesn't change your tax – it changes how HMRC handles future updates (for example, it won't be uplifted automatically by budget changes).

Tax-free allowance from this code£12,570Cumulative

Income tax with this code	£3,486
Income tax with standard 1257L	£3,486
Difference per month	£0.00

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Why you might have this code

Your income is over £100,000, so your Personal Allowance may be tapered.
HMRC needs to review items in your code, such as untaxed income or benefits.
You asked HMRC not to use a standard code (for example not to show certain income or benefit details to your employer).

What to do

Check the code HMRC holds for you in your personal tax account (GOV.UK sign-in) or the HMRC app – it also shows how the number was worked out.
Compare it with the code on your latest payslip. If they differ, ask payroll whether they have applied HMRC’s latest notice.
Check the breakdown: any deductions or additions behind the T should be listed.
If nothing seems unusual and you expected an L code, ask HMRC to review it.

See all tax codes or check your take-home with the UK salary calculator.

HMRC’s own list of reasons for a T suffix

HMRC’s PAYE Manual lists when the system gives a T instead of L, M or N. The ones most people will recognise are:

Your Personal Allowance has been tapered because your income is over £100,000 (unless the result is a K code).
Your allowances have been moved to a second job, so the main job gets T and the second job takes the single L.
A second job or pension has its own allowance-based code (not BR, D or K).
You work as a personal or domestic employee – for example a nanny employed directly by a family.
Your code includes car fuel or van fuel benefit, or other non-standard items.
Your net allowances are very small – between 1 and 19, or 0 to minus 19.
You asked for it.

Asking for a T for privacy

HMRC’s manual says some people object to an L suffix because they feel it reveals too much about their private life. In that case HMRC staff can override the L with a T and note “T suffix requested” on your record. The tax is the same. What you give up is the automatic uplift: if a Budget raises allowances, HMRC tells employers to raise all L codes at once, but T codes are reviewed by HMRC before any change is sent.

Worked example: a T code above £100,000

At £110,000, £10,000 of income above £100,000 removes £5,000 of allowance, leaving £7,570. The code is 757T. Tax for the year comes to £33,432, against £31,432 on an out-of-date 1257L.

The T stops HMRC uplifting your code automatically when allowances change. Your allowance depends on your income estimate, so HMRC needs to look at it again rather than simply add a standard amount.

What happens when a T code is cut mid-year

HMRC’s manual shows how it used to estimate the effect of reducing a code during the year. For T and K codes it assumed 10 days before the new code took effect, against 31 days for L codes. In its example, a basic-rate taxpayer’s code fell from 375T to 335T on 25 September. The £398 cut in allowances was worth £79.60 of tax over a full year, of which £39.69 related to the period already passed.

Since July 2017 HMRC works out an “in-year adjustment” instead and collects it over the months left in the year, usually on a week 1 / month 1 basis. If your T code drops and gains an M1, that’s why.

When a tapered allowance becomes a K code

HMRC’s rule gives a T to tapered allowances unless the result is a K code. At £120,000, the allowance left is only £2,570. Add a £3,000 company car benefit and the deductions exceed it by £430. Using HMRC’s K-code method (drop the last digit, then take off one), the code becomes K42 instead of a T code.

Frequently asked questions

Is a T code bad?

No. It doesn't increase your tax on its own – it means HMRC applied extra calculations or wants to review your code.

What is the difference between 1257L and 1257T?

Both give £12,570 tax-free. L is the standard allowance with no adjustments; T means other calculations are involved.

Is 0T a T code?

Not really – 0T means no allowance at all. See our 0T page.

Will HMRC change a T code automatically?

Usually not for changes like a new allowance amount; HMRC reviews it instead.

Can I ask HMRC to use T instead of L?

Yes. HMRC’s manual allows staff to override an L with a T if you feel the L reveals too much. The tax deducted doesn’t change.

I earn under £100,000. Why is my code 1257T?

Common reasons: your allowance has been moved to a second job or pension, you have fuel benefit, or HMRC wants to review items before uplifting your code. The breakdown in your personal tax account shows which.

What does 757T mean?

£7,570 of tax-free pay with a T suffix – typical for someone earning about £110,000, whose allowance has been tapered from £12,570.

Will my T code go back to L?

Yes, once the reason for it ends – for example if your income falls below £100,000, your allowance moves back to the main job, or you stop getting fuel benefit. HMRC recalculates the code and the normal suffix returns.

Does a T code mean HMRC is investigating me?

No. T simply tells payroll not to apply automatic Budget uplifts, because HMRC wants to review the code first. It’s used for routine reasons like a second job, fuel benefit or income over £100,000.

Why does my second job have a T code?

HMRC’s rules give a T to second-source codes that carry an allowance, unless they are BR, D or K codes. If the second job has part of your allowance, a T suffix is normal.

Sources

Figures are taken from official government publications and were last reviewed on 2026-10-03.