Martin Lewis has urged anybody who gets a payslip to check it right away, as they could be at risk of losing thousands of pounds if they don't.
Appearing on his Money Show Live on ITV on Tuesday, March 21, the finance guru was discussing tax codes as there's an important deadline coming up in April.
If the tax code on your wage slip is incorrect and you don't notify HMRC in time, you might lose out on a lot of money that you're owed. To help people out, Martin explained exactly how to check your tax code and what the different letters and numbers mean.