Tax code 1383M explained
What does tax code 1383M mean?
The number in a tax code shows your tax-free pay: multiply it by 10 and add up to 9. For 1383M, the number is 1383, so your tax-free pay is about £13,830 a year. The letter M tells your employer how to treat the allowance.
Your tax code does not change National Insurance. It only affects income tax.
Income tax on typical salaries with code 1383M
The table shows income tax only, using England, Wales and Northern Ireland rates for 2026/27: 20% on the first £37,700 of taxable pay and 40% above that. National Insurance and student loan are not included.
Tax code 1383M
| Salary | Income tax a year | Income tax a month | Salary after income tax |
|---|---|---|---|
| £20,000 | £1,234 | £103 | £18,766 |
| £25,000 | £2,234 | £186 | £22,766 |
| £30,000 | £3,234 | £270 | £26,766 |
| £40,000 | £5,234 | £436 | £34,766 |
| £50,000 | £7,234 | £603 | £42,766 |
| £60,000 | £10,928 | £911 | £49,072 |
| £80,000 | £18,928 | £1,577 | £61,072 |
Before National Insurance and pension contributions.
How 1383M compares with the standard code 1257L
The standard code for 2026/27 is 1257L, a tax-free amount of £12,570. Your code gives you £1,260 more tax-free pay a year, which changes your tax by about £252 a year if you are a basic-rate taxpayer.
1383M versus the standard code 1257L: the difference in tax
Compared with the standard code, your code changes how much income tax is taken. A minus sign means you pay less tax than someone on 1257L at the same salary.
1383M vs 1257L
| Salary | Tax with 1383M | Tax with 1257L | Difference a year | Difference a month |
|---|---|---|---|---|
| £20,000 | £1,234 | £1,486 | -£252 | -£21.00 |
| £25,000 | £2,234 | £2,486 | -£252 | -£21.00 |
| £30,000 | £3,234 | £3,486 | -£252 | -£21.00 |
| £40,000 | £5,234 | £5,486 | -£252 | -£21.00 |
| £50,000 | £7,234 | £7,486 | -£252 | -£21.00 |
| £60,000 | £10,928 | £11,432 | -£504 | -£42.00 |
| £80,000 | £18,928 | £19,432 | -£504 | -£42.00 |
Income tax only, England, Wales and Northern Ireland rates for 2026/27.
Emergency tax codes: W1, M1 and X
If HMRC does not have your details when you start a job, you may be given an emergency code such as 1257L W1 or 1257L M1. These calculate tax on each pay period alone, ignoring your pay so far this year, which can take too much tax at first. HMRC normally corrects it within a few pay periods once your employer sends the right information, and any overpayment is refunded.
What to do if your tax code looks wrong
- Check it on your payslip, P45 or P60, or in your personal tax account on GOV.UK.
- Tell HMRC about changes in income, benefits or a second job.
- If you have paid too much tax, HMRC will usually refund it after the end of the tax year, or earlier if the code is corrected.
- You can ask HMRC to correct a code that uses an emergency basis (W1, M1 or X).
Sources and further reading
Questions people ask
What is tax code 1383M?
How much tax will I pay with code 1383M on £30,000?
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Results are estimates for information only, not financial advice. Read the full disclaimer.