Couples married for five years could claim more than £1,000 from HMRC

Around 700,000 couples could be missing out on a tax refund from HM Revenue and Customs.

Thanks to a tax break known as the marriage allowance, couples who are married or in a civil partnership can lower their tax bills in certain circumstances.

Eligible couples who have been married or in a civil partnership for the past five years but haven't yet claimed their allowance could now get a rebate of £1,150.

Here, we explain how the marriage allowance works and who could qualify for a rebate.

What is the marriage allowance?

Introduced in 2015, the marriage allowance is a government scheme designed to give tax relief to couples who are married or in a civil partnership

It allows a non-taxpaying spouse to transfer £1,250 of their personal allowance (the amount you can earn each year before tax is due) to their partner.

Who is eligible for the marriage allowance?

You can claim the marriage allowance if:

• You're married or are in a civil partnership
• One of you does not pay income tax (your income is below £12,500)
• One of you is a basic-rate taxpayer (your income is between £12,500 and £50,000 - or £43,430 if you live in Scotland)

Take the quiz below to work out whether you're eligible for the marriage allowance.

How much marriage allowance can you claim?

The marriage tax allowance for 2019-20 will cut an eligible couple's tax bill by £250.

The example below shows how the marriage allowance is calculated, where one partner is a non-taxpayer earning £8,000 and the other is a basic-rate taxpayer earning £30,000.

Partner 1 (basic-rate taxpayer)

Partner 2 (non-taxpayer)

It is possible to backdate your claim by up to four years.

This means that eligible couples who have been married or in a civil partnership for the past five years could now claim up to £1,150.

The table below shows the value of the marriage allowance since it was introduced in 2015.

• Find out more: tax-free income and allowances

How is the marriage allowance paid?

HMRC will usually adjust the tax code of the basic-rate taxpayer to reflect the extra allowance.

If you're self-employed, the allowance will reduce your bill when you complete your self-assessment tax return.

Backdated sums will be paid out as a lump sum, usually as a cheque, after you've submitted your application.

• Find out more: understanding your tax code

How to apply for the marriage allowance

You can apply for the marriage allowance online at Gov.uk.

The person with the lower income should make the claim, as they're the one transferring part of their personal allowance.

Both partners will need to provide their national insurance numbers. The non-taxpayer will also need to provide one of the range of acceptable forms of ID required.

You can also make a claim via phone by calling 0300 200 3300.

Alternatives to the marriage allowance

If either of you were born before 5 April 1935, you'll need to claim a separate tax break called the married couple's allowance, which works quite differently.

The married couple's allowance doesn't increase the amount you can earn tax-free. Instead, it reduces your tax bill by 10% of the allowance you're entitled to.

If you receive the minimum allowance of £3,450 in the 2019-20 tax year, your tax bill will be cut by £345.

This scheme is currently being phased out by HMRC, but for more information on how it works and the best way of applying, check out our married couple's allowance guide.