Why do I have an M or N tax code?
The letters M and N are used in a tax code when the marriage tax allowance is being claimed by a couple who are employed under PAYE.
HMRC uses the letters M and N to show if you are either receiving or transferring the marriage allowance.
- If your tax code ends in M it confirms that you have received a 10% transfer of your partner’s personal allowance because of the marriage allowance. An example tax code would be 1234 LM.
It’s important not to confuse the M code with the similar M1 which is used to deduct emergency tax.
- Letter N is used for the partner who has transferred 10% of their personal allowance due to the marriage tax allowance being awarded. An example of an MA transferees code is 1234 LN.
The marriage tax allowance is available to couples who are married or in a civil partnership and you need to apply for it to claim it back.
If you meet the criteria your tax code will be changed by HMRC after your application has been approved.
After you have had notification that the marriage tax allowance has been granted it takes around two months for codes to adjust.
You should check for either the letter M or N showing at the end of your tax code on your next payslip or check your personal tax account for coding notifications.
HMRC will generate a new tax code for each MA claimant and send your new tax code to your employer so they can start using it in your next pay.
Does the letter N mean I pay more tax?
The person who transfers the marriage tax allowance will have a reduced personal allowance which may mean they pay more tax as an individual.
In theory the lower earner who receives the allowance should reduce their tax bill enough to mean that overall less income tax is paid as a couple.
As a couple it’s important to review whether the MA should be claimed if your circumstances change so you can tell HMRC to stop the allowance.
If earnings increase it might mean you become ineligible and shouldn’t continue to claim the MA.
Telling HMRC to stop the allowance avoids a future tax bill if you have received the allowance when you weren’t entitled.
How to check and amend your marriage allowance tax code
You will be notified by HMRC about amendments to your tax code and given an explanation what the letters mean at the end of it.
To see if your tax code has been updated with the MA or you have other questions about your code HMRC has online services which are often the quickest way to contact them, or you can call 0300 200 3300 during weekdays.
Apart from the marriage tax allowance checking your personal allowance generally to make sure it includes all of the available reliefs and tax allowances is recommended.
How to claim the marriage tax allowance
The application process can be done online via .GOV which is usually the quickest option or you can use the postal form MATCF.
When you claim the marriage tax allowance you have the option to backdate it to previous tax years which could trigger a tax refund from HMRC.
If you are granted the allowance for multiple years you should receive a P800 tax calculation giving you a breakdown of any tax refund owed and how you will receive the repayment of tax.
