What happens if I miss the deadline for filing my self-assessment tax return?

If you miss the deadline to file your self-assessment tax return, you will have to pay penalties in accordance with how late you are. We have broken these down previously in our guide. However, you can expect to pay a fixed £100 penalty fee for the first day it’s late and then £10 per day for a maximum of 90 days or three months. 

If the return is between 6 and 12 months late, you will be charged a fee of 5% of the tax you owe, potentially 100% if the payment is passed 12 months.