How far back can you amend a tax return uk
- Amendment window closes 31 January
- 2,028
- Effect on the bill for that year
- -£400
- Effect on each payment on account that follows
- -£200
- Effect on the next 31 January payment
- -£600
The rates, thresholds and deadlines these sheets apply are HMRC's published figures for the tax year you select; everything else is arithmetic on the numbers you typed.
The figures shown are a worked example (2,028); yours replace them as you type.
Download the How far back can you amend a tax return uk worked example (CSV)
A Self Assessment return you have already filed is not final. You can change it yourself for 12 months after the 31 January online filing deadline for that tax year, which in practice means most of a second year to correct a figure you got wrong or a cost you forgot. This sheet takes the tax year and tells you the date the amendment window closes, what happens to the bill when the figure moves, and what to do when the window has already shut.
What somebody filing their own return asks about the How far back can you amend a tax return uk
How long do I have to change a return?
12 months after the 31 January online filing deadline for that tax year. Enter the year in the sheet and it prints the exact closing date rather than leaving you to count.
What happens if the amendment window has closed?
You can no longer amend the return itself. A claim for overpayment relief is the route for tax you have overpaid, and it has its own, longer time limit; a genuine underpayment should be disclosed rather than left. Both are worth an adviser.
Does amending a return change my payments on account?
It can. Payments on account are set from the previous year's bill, so a change to that bill moves the instalments that follow it. The estimator on this site shows the instalments the amended figure produces.
Where the constants in this tool come from
GOV.UK: Self Assessment tax returns - if you need to change your return.