Self-Assessment is a method of paying income tax to HMRC, usually if you are self-employed, but people with other income may need to submit a self-assessment tax return too.
You can submit a self-assessment tax return to HMRC either online or with a paper form.
There are deadlines for completing your self-assessment. Paper returns need to be submitted by 12pm 31st October after the tax year and online tax returns need to submitted by 12pm 31st January after the tax year.
More information on self-assessment can be accessed on gov.uk: