Yesterday (October 31) was the deadline for submitting your paper tax return for the year ended 5 April 2017.
Don't panic if you've missed the deadline, you have until 31 January 2018 to submit the return online - by the way you only have 92 days left to complete it at today's date. Click here if you're reading this at a later date to see how many days are remaining.
Finally, don't whatever you do submit a paper return now. HMRC won't reject it they'll fine you £100 because it's late.
Welcome to cloud cuckoo land.