Self-Assessment filing deadlines
The 2020-21 tax return deadline for submitting your paper Self-Assessment returns was 31 October 2021. The tax deadline for submitting online returns is 31 January 2022. Late submission of a Self-Assessment return will become liable to a £100 late filing penalty. The penalty usually applies even if there is no liability or if any tax due is paid in full by 31 January 2022.
If you are still submitting paper tax returns, we would recommend that you consider the benefits of submitting the returns electronically. This includes gaining an additional three months (until 31 January 2022) in which to submit your return. You will also receive instant confirmation that a return has been filed and not need to rely on the vagaries of the postal service.
If you received a letter informing you to submit a paper return after 30 July 2021, then you have an extended deadline which runs for three months from the date you received the letter to submit a paper return.
It is also important to remember that taxpayers are required to declare if they received any grants or payments from COVID-19 support schemes up to 5 April 2021 (i.e., during the 2020-21 tax year) as these are taxable. If you received furlough payments, then these should be reflected on your P60 form. Details of any Self-Employment Income Support Scheme or received Coronavirus Job Retention Scheme grants will need to be included on your Self-Assessment form. The £500 one-off payment for working households receiving tax credits does not have to be reported as part of the Self-Assessment submission.
Source: HM Revenue & Customs | 17-10-2021