Self Assessment tax return SA100 forms

If you’re self employed, run a business or have income from other sources, then you may be required to complete an SA100 form.

Form SA100 is the official name for a UK self assessment tax return form. Millions of UK tax payers complete a self assessment tax return every year and it’s used to provide information on individuals income to HMRC, so HMRC can work out how much tax is owed.

In this blog we explain more about the SA100 self assessment tax return, the information required and how to complete and file the tax return.

What is an SA100 form?

Self assessment relates to the process you go through to submit information about your income to HMRC. The SA100 form is a multi-page form you are required to fill out to complete the self assessment tax process.

The SA100 form is used to report your income from all sources during a tax year, any capital gains you’ve made from the sale of items and to claim tax reliefs and any repayment due to you.

Depending on the complexity of your income, you may have to complete supplementary pages to provide HMRC with further information. These supplementary pages will go into much more detail around specific income sources or capital gains.