The short version: If you miss the Self Assessment deadline, HMRC charges a late filing penalty. It starts at £100 even if you owe no tax, and it goes up the longer you leave it.
How much are the penalties?
Miss the deadline by one day and it’s £100. After three months, HMRC adds daily penalties. After six months and twelve months, more fixed penalties get added. A full year late can cost you over £1,600 in penalties alone, plus interest on any tax owed.
What if I don’t owe any tax?
You still get fined for filing late. The penalty isn’t linked to how much tax you owe. If you were required to file a return and didn’t, the penalties apply regardless.
Can you appeal?
Yes, if you have a reasonable excuse. Serious illness, bereavement, HMRC’s own errors. “I forgot” or “I didn’t know” usually won’t cut it. Appeals need to be made promptly with evidence.
Limited companies are different
Company accounts filed late to Companies House have their own penalty structure, separate from Self Assessment.
Facing a late filing penalty and not sure what to do? Get in touch and we’ll help you sort it out.
