Why is my new tax code different from the previous tax year?

Previously I was on the code 552L. I just received al letter informing me about my new tax code for the upcoming tax year.





Why the change in the code? None of my circumstances change apart from that I'm earning slightly more at the moment.

Why is my new tax code different from the previous tax year?
What did you have extra included in your code number to put you up to 552L? Expenses incurred in employment? Professional subsciptions? Most people are on 522L, rising to 543L in April, due to budget uprate. You didn't tell us what your new tax code is, so we are just guessing. I would expect your code to rise by 21 in normal circumstances. Whatever code is used, it automatically calculates extra tax due to increased earnings.
Reply:Progress!
Reply:Any unpaid tax from last year will raise your code to pay it this year.
Reply:The tax-free allowance changes every year. Why were you on 552L anyway? Almost everyone else has been on 522L.