Has anyone reclaimed overpaid tax after finding the wrong tax code?

[UknownM]

Millions of UK workers are on the wrong tax code, and you can claim back up to 4 years of overpaid tax.

The standard 2026/27 code is 1257L (£12,570 Personal Allowance, frozen to April 2028). If yours is different it might be right, but it's worth a check.

Codes that often signal over-collection:

• BR: 20% on everything, no Personal Allowance. Common when an old benefit or second job got stuck on it.
• 0T: no allowance, basic/higher/additional rates. Usually emergency from a job started without a P45.
• D0 / D1: 40% / 45% on everything from that source.
• K-codes (e.g. K475): negative allowance, extra tax. Often caused by old company benefits or unpaid prior-year tax that should have cleared by now.
• Anything ending W1, M1 or X: emergency. Should switch back to normal once HMRC has your details.

How to check: payslip, P60, or sign in to gov.uk/check-income-tax-current-year.

If you've overpaid, HMRC sends a P800 letter after each tax year. Refunds go through the gov.uk personal tax account, usually within 5 working days. You can claim back up to 4 tax years.

Your employer cannot change your code. It has to come from HMRC.

Full list + how to fix: trendingsheet.com/article/uk-tax-code-2026-27-1257l-wrong-code-hmrc-refund-p800

Anyone here pushed a back-refund through, and how many years back did you go?

I’m owed nearly 12 months worth of overpaid tax - I left my old job, had a benefit and stopped getting that when I left. They haven’t told me how I can claim it back at all. It’s only worth about £36 but it’s the principle of it isn’t it? If you owe them money they’ll be on it to get it off you as soon as possible, but they won’t tell you how to get back the money they’ll owe you!