Your tax code determines how much income tax you pay — and whether you’re getting your full tax-free personal allowance (£12,570 for 2025/26).

HMRC updates your code whenever your circumstances change, so it’s important to be aware of why and when your tax code might change.

Common reasons your tax code might change:

• You’ve started a new job or begun receiving a pension
• You’ve started claiming taxable state benefits
• You’ve gained or lost company benefits (like a car or private healthcare)
• You’ve transferred Marriage Allowance to or from your partner
• You’ve claimed work-related tax reliefs or expenses.

Even a small change in your situation can affect your tax code — and an incorrect code could mean you’re paying too much or too little tax.

Take a minute to check your tax code on your latest payslip or HMRC account.

If you’d like help understanding your code or recent changes, please get in touch— we’re always happy to help.

Internet link: GOV UK