Register with HMRC as soon as possible after you become self-employed. A penalty may be charged if you fail to do so by 5 October (for tax purposes) or 31 January (for national insurance contributions) after the end of the tax year in which you started the business. To register, fill out the online registration form ( www.gov.uk/log-in-file-self-assessment-tax-return/register-if-youre-self-employed ) or ring the self-employed helpline (0300 200 3500; Relay UK 18001 then 0300 200 3100). You will be asked to complete a tax return each year. You can find more information at www.gov.uk/working-for-yourself . If you received any support grants from the government during the coronavirus pandemic, check whether they need to be included on your self-assessment tax return.