Ever looked at your payslip and wondered why it says “1131N” instead of the usual “1257L”?
You’re not alone. Most people never check their tax code until something looks off. Let’s break it down in plain English so you can finally understand what tax code 1131N means, why you might have it, and what to do if it’s wrong.

What a tax code actually does

Your tax code tells your employer or pension provider how much of your income should be tax-free before PAYE tax is taken.
The numbers in the code show the value of your tax-free allowance, and the letter at the end explains any special situation — like if you’re married, have more than one job, or are on emergency tax.

What does 1131N mean?

The code 1131N has two parts:

• 1131 = You can earn £11,310 tax-free this year.
  (The standard allowance is £12,570, so yours is slightly lower.)
• N = You’ve transferred part of your allowance to your spouse or civil partner through the Marriage Allowance scheme.

So, if you see 1131N on your payslip, it means you’ve chosen to give away 10% of your Personal Allowance to your partner so they can save on tax. You pay a little more, but together you both save overall.

How the Marriage Allowance works

The Marriage Allowance lets one partner transfer 10% of their Personal Allowance (about £1,260) to the other partner, as long as:

• You’re married or in a civil partnership
• One of you earns less than £12,570
• The other is a basic-rate taxpayer (earns less than £50,270)

That transfer reduces the higher earner’s tax by around £252 a year.
If you’re the partner giving away your allowance, your code becomes 1131N.
If you’re the one receiving it, your code becomes something like 1383M.

How 1131N affects your take-home pay

Because your allowance is slightly lower (£11,310 instead of £12,570), you’ll pay a little more tax each month – roughly £20–25 depending on your income.

But don’t worry – your partner’s code (with the extra allowance) means your household still saves money overall.

It’s a small sacrifice for a shared win.

When to double-check your tax code

Your code can stay the same for years, but sometimes life changes mean it needs an update.
Check your code if:

• You’ve started earning more and no longer qualify for Marriage Allowance
• Your partner’s income has changed
• You’ve separated or divorced
• You’ve started getting a company car, pension, or new job
• You notice your take-home pay suddenly drops

You can check or update your code anytime using HMRC’s online service at Check Income Tax Current Year.

A quick example

Let’s say you earn £15,000 a year and your partner earns £30,000.

1. You transfer £1,260 of your allowance to your partner.
2. Your allowance drops to £11,310 (tax code 1131N).
3. Your partner’s allowance increases to £13,830 (tax code 1383M).
4. They save 20% of £1,260 = £252 in tax.

Simple – one couple, two codes, joint savings.

Common mistakes people make

• Assuming it’s automatic – You have to apply for Marriage Allowance; it doesn’t happen by itself.
• Forgetting to cancel it – If your income rises above £12,570, you could end up overpaying.
• Not updating HMRC – Life events (new job, retirement, separation) can make the code wrong.

How to fix a wrong tax code

If you think your tax code is wrong, don’t panic.
Here’s what to do:

1. Check your payslip or P60 – confirm it says 1131N.
2. Log in to HMRC’s Personal Tax Account – see what they have on record.
3. Tell HMRC about any changes (income, marriage, separation, etc.).
4. Speak to your accountant if you’re unsure — they can request a correction on your behalf.

HMRC usually updates your code within a few days and any refund or adjustment is handled automatically.

At AccounTax Zone, we make taxes human again

Understanding your tax code shouldn’t feel like reading another language.
Our team at AccounTax Zone helps individuals and business owners across the UK make sense of their PAYE, allowances and tax planning — so you never pay more than you should.

Whether you’ve just noticed 1131N on your payslip, or you’re wondering if Marriage Allowance is still right for you, we can:

• Review your PAYE and coding notice
• Identify any over- or under-payments
• Help you claim or cancel Marriage Allowance correctly
• Deal directly with HMRC for you
  

Call us today on 020 3740 7074 or email at info@accountaxzone.com to book a free tax-code review. Or directly book your meeting HERE!

Key takeaway

Tax code 1131N simply means you’ve given 10% of your Personal Allowance to your partner.
You pay a bit more, but together you both save.
Still, check every year — circumstances change, and the right code means the right tax.

You may also like to read: Checking your tax code