Carry forward is a rule that lets you contribute more than the standard annual pension allowance (currently £60,000) by using unused allowances from the previous three tax years - without facing an annual allowance charge.
To use carry forward, you must:
Have been a member of a UK pension scheme in each of the years you're carrying forward from
Have already used your full annual allowance in the current tax year
Earn at least the total amount you want to contribute that year
Use the oldest unused allowance first
Not have triggered the Money Purchase Annual Allowance (MPAA) - if you have, carry forward doesn’t apply
You'll also need to handle this via self-assessment.
Still unsure? Carry forward rules can be complex, so if you're in any doubt, it's best to seek professional tax or pension advice to make sure it's right for your situation.