It's been around since David Cameron introduced it in 2015, but many married couples may not know that they could lower their tax bills thanks to a special tax break.
The Married Couple's Allowance could reduce your tax bill each year if you're married or in a civil partnership.
The amount it could save you is £252.
Firstly, some jargon we're going to mention a few times...
Your personal tax allowance is the amount you can earn tax-free each tax year
For most people the personal allowance is £12,570 - this is the basic income tax threshold
Basic rate taxpayers earn less than £50,270, or £43,662 in Scotland.
With these definitions in mind, marriage allowance works by allowing a partner earning less than the basic income tax threshold of £12,570 to transfer some of their personal tax allowance to their higher earning partner - as long as they're a basic-rate taxpayer earning less than £50,270.
You can transfer up to £1,260 of your personal tax allowance to your husband, wife or civil partner to cut their tax bill.
A simple example...
Your income is £8,500, so you do not pay income tax. Your partner's income is £20,000. You both have the standard tax allowance of £12,570.
This means your partner pays tax on £7,430.
After claiming marriage allowance, £1,260 of your personal tax allowance is transferred to your partner. That brings their personal tax allowance to £13,830 - meaning they only pay the 20% income tax on £6,170.
This saves them £252.
It's worth noting that if you earn less than £12,570, but more than £11,310 (the personal allowance minus the transferrable £1,260), you may end up paying some tax if you transfer your allowance - but you'll still save money as a couple. If you fall within this bracket, it's worth doing more research.
What if I've only just learnt I can get it?
If you've been eligible for marriage allowance for a while but have only just realised you can claim it, don't worry. You can backdate your claim to include any tax year since 5 April 2019.
Your partner's tax bill will be lowered depending on their personal tax allowance rate for the years you're backdating.
You can still claim the allowance if your partner has died since then.
How do I apply?
You can apply for marriage allowance on the government website.
Make sure you have a Government Gateway account before you go to make your claim.