How long to keep your records
You must keep records about your business income and costs for longer if you’re self-employed.
How long you should keep your records depends on whether you send your tax return before or after the deadline.
HM Revenue and Customs (HMRC) may check your records to make sure you’re paying the right amount of tax.
Tax returns sent on or before the deadline
You should keep your records for at least 22 months after the end of the tax year the tax return is for.
If you send your 2017 to 2018 tax return online by 31 January 2019, keep your records until at least the end of January 2020.
Tax returns sent after the deadline
You should keep your records for at least 15 months after you sent the tax return.