Can I appeal a late filing penalty?

Yes, in certain circumstances. HMRC accepts appeals based on a 'reasonable excuse' — things like serious illness, bereavement, or a technical failure on HMRC's own systems. You normally need to appeal within 30 days of receiving the penalty notice. HMRC doesn't usually accept forgetting about the deadline, finding the form too difficult, or relying on an accountant who didn't file on time as reasonable excuses. If you think you have valid grounds, you can appeal online through your HMRC account or by writing to HMRC. Not sure if your situation qualifies? Message us on live chat.