A tax code change affects your take‑home pay and usually happens when HMRC updates your income information.
Common causes
- New job
- Benefits in kind
- Underpaid tax
- Emergency tax code
1. New job
HMRC updates your income automatically.
Quick fixes:
- Check your P45/P60
- Compare codes from old and new jobs
2. Underpaid tax
HMRC adjusts your code to recover it.
Quick fixes:
- Check for “adjustment” notes
- Review last year’s tax summary
3. Emergency tax code
Happens when HMRC lacks information.
Quick fixes:
- Submit your P45
- Update details on HMRC app
What to try first
Check your payslip for the new code and compare it to last month’s.
When to contact HMRC
If the code looks incorrect or unexplained.