This will depend on the date the return was issued to you. For returns sent out on or before 31 July, the deadlines for completion are:
- 31 October for paper returns; or
- the following 31 January, if you are filing online.
If you are sending a paper return, an automatic penalty of £100 will be charged for late submission. This applies even if you have no tax to pay or have paid the tax you owe.
If you are filing a paper return, and you want to guarantee that HMRC will be able to process your return and tell you the amount of tax payable on the following 31 January, you need to have submitted the paper version of your tax return by 31 October.
If you want to have your tax liability (where it is under £3,000) collected through your code number, you need to have submitted your paper tax return by 31 October or your online tax return online by 30 December.
You can still ask HMRC to do this for you up to the end of November, but there is no guarantee that they will do so if your return has been filed later than 31 October. Different dates apply if you have received a return or notice to file after 31 July. More information about this is available on the GOV.UK web site.