Money expert Martin Lewis has set out how people to boost their tax-free Personal Allowance rule via HMRC. Returning on the latest episode of The Martin Lewis Money Show Live on Tuesday, February 10, Martin set out the handy boost available to married couples and those in a legal civil partnership.

Crucially, this tax-free Personal Allowance increase only applies to those who are married, it is not claimable by cohabiting couples. The way it works is, if one person in the marriage is earning less than the Personal Allowance (£12,570) and the other above it, the person earning below the threshold can apply to move 10% of their taxable income to the other.

This can be useful in marriages where for example one partner isn’t working, such as for childcare, as it will collectively save the pair money on tax by moving some of the tax allowance to their earning partner, allowing them to pocket more of their earnings before they start paying tax.

Martin Lewis said: “We’re gonna talk about the £1,260 marriage tax break, the Marriage Tax Allowance. It works for married couples generally under the age of 90 because there’s a different marriage benefit if you’re over the age of 90.

“So here’s how it works, it has to be a non-taxpayer, so that’s someone earning under the £12,570 a year Personal Allowance, the amount that you can earn each year tax-free, married to a basic rate 20% taxpayer.

“The non-taxpayer can go to gov.uk and apply to give 10% of their Personal Allowance to the taxpayer.

“So they now get both. Which means, the net effect is, the non-taxpayer now has £11,310 a year they can earn tax-free, which will hopefully cover most of what they do earn.

“And the taxpayer has this extra £200 which is £13,830 per year. The gain of that, this year, is £252, because they’ve got £1,260 they’re not paying 20% tax on that they would have otherwise.”

“The times five, is crucial. Because with the Marriage Tax Allowance you can back claim four tax years, so you can get this tax year, which is done by altering your tax code, and you can go back four prior tax years, which is about £1,000 benefit…”

The Martin Lewis Money Show Live February 10 episode is still available to watch back via catchup service ITVX.