Expenses if you're self-employed
How to claim expenses
Keep records of all your business expenses as proof of your costs.
Tell HM Revenue and Customs (HMRC) your allowable expenses for the tax year on your Self Assessment tax return.
You do not need to send in proof of expenses when you submit your tax return. But you should keep proof and records so you can show them to HMRC if asked.
You must make sure your records are accurate.