Tax code

Martin Lewis urges workers to check their tax code after NI jump

Money-saving expert Martin Lewis has warned millions of workers to check their tax code is correct or they could lose thousands of pounds.

HMRC uses your tax code to determine the amount of your monthly salary.

It is made up of numbers and letters that tell your employer or pension fund what tax to withhold.

But the team behind Money Saving Expert (MSE) suggested “millions of codes could be wrong”.

Martin Lewis, Money Saving Expert


It comes as National Insurance contributions increased by 1.25 percentage points from 12% to 13%.

The threshold at which you start paying has risen from £9,568 to £9,880 and is expected to rise to £12,570 in July,

How to check your tax code

You should have recently received a letter from HMRC with your new tax code.

But if you haven’t, you can find your tax code on your last payslip or on your P45 if you recently quit your job.

You can also find it at, but you must first register for a government gateway ID.

Use the free MSE tax code calculator

MSE has updated its tax code calculator which people can use to check if their tax code for this year is correct.

To verify yours, all you need to do is enter your pre-tax income and your current tax code.

The most common code for the current tax year is 1257L for people who have a job or a pension.

How to Claim a Tax Refund

If you think you have the wrong tax code you can contact HMRC on 0300 200 330 or speak to an adviser online via their live chat service.

HMRC will contact your employer to correct your tax code and you can recover the money you overpaid in tax on your next payslip.

You can also claim up to four additional years if you have overpaid for a period of time.