How much is the 1383M tax code worth?

£252 a year for 2026/27. The code adds £1,260 to your Personal Allowance and that £1,260 would otherwise be taxed at the 20% basic rate, so £1,260 x 20% = £252, or about £21 a month.

What happens if I start earning over £50,270?

You stop being eligible. HMRC normally cancels the transfer and moves you back to 1257L, and your partner back to 1257L too. Tell HMRC rather than waiting, or you may end up owing the relief back.

Can we claim for previous years as well?

Yes, Marriage Allowance can be backdated up to four tax years where you met the conditions in each of them. Earlier years are paid as a refund rather than through the tax code, so your current code stays 1383M.

Tax Code · 2026/27

1383M Tax Code 2026/27: You Received Marriage Allowance

1383M is the code of the partner who received Marriage Allowance. The M suffix means £1,260 of your husband, wife or civil partner’s Personal Allowance has been added to your own £12,570, giving £13,830 - which is where 1383 comes from.

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What the 1383M tax code means

The number is your enlarged allowance divided by 10: £12,570 plus the £1,260 transferred in gives £13,830, so the code reads 1383. The 'M' means you are the receiving partner. Your spouse will be on the matching 'N' code, 1131N.

Because the extra £1,260 would otherwise have been taxed at the basic rate, the code is worth £1,260 x 20% = £252 a year to you. That is the whole value of Marriage Allowance, and it does not change with your income as long as you stay a basic-rate taxpayer.

The relief is not proportional and it is not a doubling of the allowance. Only £1,260 can move, however much of their allowance your partner is leaving unused.

When you'll see 1383M

Your spouse or civil partner applied to transfer part of their Personal Allowance to you.
Your income falls in the basic-rate band, between £12,571 and £50,270 for 2026/27 in England, Wales and Northern Ireland.
In Scotland the eligibility test is the starter, basic or intermediate rate rather than the basic rate, so the income range differs.
HMRC applies the code from the following tax year, or mid-year with backdating where the claim covers earlier years.

What to do if you have a 1383M code

Check your income is still under £50,270. Once you become a higher-rate taxpayer you are no longer eligible and HMRC will remove the transfer.
Check the £252 is actually reaching you. Compare your tax against the same salary on 1257L: you should be paying £252 less over the year, or £21 a month.
If your partner has started earning above the Personal Allowance, do the household arithmetic again. The transfer can end up costing them more than it saves you.
The transfer renews automatically, so there is nothing to do each year unless your circumstances change.

Worked example

Priya earns £34,000 and is on 1383M after her husband Sam transferred £1,260 of his allowance. Her tax-free amount is £13,830 rather than £12,570, so she pays 20% on £20,170 instead of £21,430. That is £4,034 of Income Tax instead of £4,286 - a saving of £252 for the year, about £21 a month. Sam, on £9,000, still pays nothing.

Want to see the numbers for your own salary? Use the salary calculator and pick 2026/27 to see how 1383M interacts with your full take-home.

Frequently asked questions about 1383M

How much is the 1383M tax code worth?: £252 a year for 2026/27. The code adds £1,260 to your Personal Allowance and that £1,260 would otherwise be taxed at the 20% basic rate, so £1,260 x 20% = £252, or about £21 a month.
What happens if I start earning over £50,270?: You stop being eligible. HMRC normally cancels the transfer and moves you back to 1257L, and your partner back to 1257L too. Tell HMRC rather than waiting, or you may end up owing the relief back.
Can we claim for previous years as well?: Yes, Marriage Allowance can be backdated up to four tax years where you met the conditions in each of them. Earlier years are paid as a refund rather than through the tax code, so your current code stays 1383M.

All UK tax codes →

Sources & further reading

All figures and definitions on this page reflect the 2026/27 UK tax year and are cross-checked against HMRC guidance.

HMRC — What your tax code means (official meanings for L, BR, D0, D1, K, 0T, NT, M, N, S, C, T)
HMRC — Income Tax rates and Personal Allowance (2026/27 bands and thresholds)
HMRC — Emergency tax codes (W1, M1 and X suffixes)
HMRC — Rates and thresholds for employers 2026 to 2027
HMRC — Your Personal Tax Account (check your current code and how it was calculated)
Our methodology & calculation sources →