Money expert Martin Lewis has warned workers that they must check the tax code on their payslip now or face the risk of being ‘slapped across the face with a big tax bill’.

Speaking on the latest episode of The Martin Lewis podcast, Martin explained how it’s your responsibility to check you’re on the right tax code, even if you work a regular PAYE job, because if HMRC realises later on that you’ve underpaid tax, it won’t be your employer that gets the blame.

In fact, if you’re on the wrong tax code, you will have to find the money to pay the bill and you could even face interest charges or a fine for failing to pay.

Not just for the self-employed, your tax code is actually printed on your payslip, even a digital payslip, and informs HMRC how much tax you should be paying on your weekly or monthly wages.

Martin Lewis said: “Do you know what your tax code is? If you’re an employee you need to, because millions of them are wrong each year and if they are wrong, legally it’s your responsibility not your employer’s and not HMRC’s, to ensure it’s correct.

“Now a typical tax code is 1257L, take those numbers, the 1257, add a 0 to the end so you’ve now got £12,570. That’s how many pounds you can earn each year before you have to start paying income tax.

“So that’s the standard tax-free allowance of £12,570 a year. The L or the letter is the different category of tax that you’re in. Now I say millions of them are wrong and they are, and think about the impact of that.

“It could mean you’re paying far too much tax each year. You don’t want that. It could also mean, you’re paying too little tax. Sounds good? It isn’t, because at some point they WILL catch up and make sure you pay the tax that you owe.

“So you could be hit, slapped across the face, with a big tax bill and not have the cash to pay it, which is a nightmare.

“So, each year when you get your tax code you should check it, and if you’ve never checked it before, it’s worth going and finding it now and doing a check.

“There are tax code calculators online that will help you do so.”

The Martin Lewis Podcast is still available to listen to via BBC Sounds, Spotify and Apple Music.