You should check your tax code at least once a year,but in practice, there are a few key moments when you really should double-check it:

At the start of a new tax year (UK tax year starts 6 April)

• HMRC often issues new codes then.

Whenever you change jobs

• Employers get your code from HMRC, but errors happen.

If your income changes significantly

• Pay rises, bonuses, going part-time, second job.

If you start/stop receiving benefits or pensions

• These can alter your allowances.

After claiming expenses or reliefs

• These should be reflected in your code, but aren’t always.

If HMRC sends you a new tax code notice

• Always check it carefully.