Last reviewed January 2023

A tax code is a string of numbers and letters that tells your employer how your earnings should be taxed. You get one for each Pay As You Earn (PAYE) job you have, and it’s important to keep track of them. Any time your tax code changes, HMRC will alter the Income Tax you’re paying each year.

If you’ve been given a D1 tax code, it basically means you’re being taxed at the additional rate of Income Tax (45%) on all of your income from this job, without the benefit of a tax-free Personal Allowance!

In all likelihood, there’s no reason to panic about getting a D1 tax code. The reality is it probably just means that you’ve got more than one job, and your Personal Allowance is being applied to the other one. On top of that, it obviously means you’re earning enough to pay Income Tax at the additional rate of 45%.