Tax Code 0T M1 Explained

0T M1 – sometimes shown as 0TM, 0T W1 or 0T X – is an emergency tax code. You get no Personal Allowance and each pay period is taxed on its own (non-cumulative). Employers use it when a new starter has no P45 and hasn't completed a starter checklist, so it usually overtaxes you until HMRC sends a proper code.

Tax-free allowance implied by this code: £0 a year (£0.00 a month).

How your pay is taxed on 0T M1

Each month you get no tax-free pay, 1/12 of the basic-rate band (£3,141.66) at 20%, and anything above at 40%. Example (England, £2,500 a month): £2,500 × 20% = £500 tax, versus £290.50 on 1257L – roughly £209.50 overpaid every month. Earn £4,000 one month and the slice above £3,141.66 is taxed at 40%. Because it is non-cumulative, nothing is refunded through payroll until your code changes.

Tax-free allowance from this code£0Cumulative

Income tax with this code	£6,000
Income tax with standard 1257L	£3,486
Difference per month	£209.50

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Why you might have this code

You started a new job without a P45 and no starter checklist was completed.
Your employer could not tell HMRC which starter statement (A, B or C) applies to you.
You started a new pension and the provider had no code from HMRC.

What to do

Give your employer your P45 or complete the PAYE starter checklist straight away.
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.
If it is still 0T M1 after around 35 days, contact HMRC or update your employment in the HMRC app.
Overpaid tax is usually refunded in your next pay after a cumulative code arrives; otherwise expect a P800 after 5 April.

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

What 0T M1 deducts month by month

Because 0T M1 looks at each payday on its own, uneven pay moves your tax around a lot. The table follows four months of variable pay (overtime in month 3) in England. Each month gets £3,141.67 of basic-rate band and no tax-free pay. Anything above that is taxed at 40%, even though over a full year you’d be nowhere near the higher-rate threshold.

Over the four months 0T M1 takes £2,411.67, compared with £1,402.00 on 1257L M1 – an overpayment of £1,009.67 that payroll can’t refund while the code stays non-cumulative.

Pay period	Gross pay	Tax on 0T M1	Tax on 1257L M1
Month 1	£2,200	£440.00	£230.50
Month 2	£2,600	£520.00	£310.50
Month 3	£4,000	£971.67	£590.50
Month 4	£2,400	£480.00	£270.50

Weekly pay on 0T W1

On a weekly payroll, 0T W1 gives no tax-free pay and £725.00 a week of basic-rate band. On £600 a week that means £120.00 of tax, against £71.65 on 1257L W1. That is £48.35 extra each week until the code changes.

People who are meant to be on 0T M1

HMRC’s employer guidance tells payroll to use 0T on a week 1 or month 1 basis for anyone it pays only once – a one-off fee, for example. The employer enters “IO” in the pay frequency field of its payroll report and doesn’t issue a P45. If you did a single job for an organisation and saw 0T M1 on the payslip, that was the instruction being followed, not a mistake.

HMRC’s manual adds that where 0T week 1 / month 1 has been set as an override code, its staff shouldn’t change it until full income details for all your jobs are known. In practice, giving HMRC complete details of your jobs and pensions is what gets the code changed.

Getting the tax back

Still in the job: once HMRC issues a cumulative code, payroll refunds the overpaid tax, usually on the next payday.
Left the job and not working for 4 weeks or more, with no taxable benefits or works pension: you can claim the refund during the year with form P50.
One-off pension payment taxed on 0T M1: use P55, P53Z or P50Z, depending on whether you’ve taken all or part of the pension.
None of the above: HMRC reconciles your tax after 5 April and sends a P800 between June and March. Online refund claims are paid within 5 working days.

The Scottish version: S0T M1

GOV.UK’s employer guide lists S0T as the code for a new employee whose main home is in Scotland and who hasn’t given a P45 or enough details, so a Scottish new starter can see S0T M1. Each month starts at the 19% starter rate with no tax-free pay, then moves through one-twelfth of each Scottish band. On £2,500 a month S0T M1 deducts £507.56, compared with £500.00 on 0T M1 in England. Anything above £2,591.00 in a single month is taxed at the 42% higher rate.

Frequently asked questions

What does 0TM mean on my payslip?

It's 0T with M1 – no allowance, non-cumulative monthly basis. Some payroll software squashes it to '0TM' or '0T NONCUM'.

How much emergency tax will I pay on 0T M1?

At least 20% of all your pay, and 40% on any monthly pay above £3,141.66. On £2,500 a month that's £500.

Will I get the emergency tax back?

Yes, if you overpaid. Once your employer gets a cumulative code, the overpayment usually comes back via payroll. If not, HMRC refunds it after the year ends.

Is 0T M1 ever correct?

Rarely for long. It can be appropriate briefly for a new pension or job until HMRC has your details.

I was paid once for a short job and taxed on 0T M1. Is that allowed?

Yes. HMRC tells employers to use 0T week 1 / month 1 for employees they pay only once. If your total income for the year is under your allowance, the tax is refundable.

Why was I taxed at 40% on 0T M1 when I’m not a higher-rate taxpayer?

On 0T M1 only £3,141.67 of each month’s pay is taxed at 20%. Anything above that in a single month is taxed at 40%, whatever your annual income.

Can I claim the overpayment before the tax year ends?

Yes, if you’ve stopped working for at least 4 weeks and aren’t claiming taxable benefits – use form P50. If you’re still working, the refund comes through payroll once the code is corrected.

Is 0T M1 the same as 0T X?

Yes in effect. X is used when pay dates vary. Like M1 and W1, it means each payment is taxed on its own with no allowance.

Sources

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