Reasonable Excuse Guide

What HMRC Accepts as a Reasonable Excuse

To appeal an HMRC penalty, you need a "reasonable excuse" — an unexpected or exceptional event that was genuinely outside your control and directly prevented you from meeting the deadline.

The legal test (Perrin v HMRC)

The Upper Tribunal in Perrin v HMRC [2018] UKUT 156 established the structured test that HMRC and tribunals now follow:

  1. What facts does the taxpayer assert give rise to a reasonable excuse?
  2. Are those facts proven on a balance of probabilities?
  3. If proven, do those facts amount to an objectively reasonable excuse?
  4. Did the taxpayer act reasonably promptly once the excuse ended?

Excuses HMRC accepts

Serious illness or disability

HIGH

You were too ill to deal with your tax affairs. Medical evidence (GP letter, hospital records) strengthens your case significantly.

Bereavement

HIGH

The death of a close family member, partner, or someone you cared for prevented you from meeting the deadline.

Fire, flood, or natural disaster

HIGH

An unexpected event destroyed your records or prevented access to your premises.

Mental health condition

HIGH

Depression, anxiety, or another mental health condition prevented you from dealing with your tax affairs. HMRC has become increasingly sympathetic to these claims.

HMRC error or delay

HIGH

HMRC gave you incorrect guidance, failed to send correct forms, or caused a delay that prevented you from meeting the deadline.

Computer or software failure

MEDIUM

HMRC's online service was unavailable, or your computer/software failed near the deadline. Stronger if close to 31 January.

Postal delays

MEDIUM

You posted your return or payment in good time but it was delayed or lost. Proof of posting is important.

Domestic emergency

MEDIUM

A sudden crisis such as relationship breakdown, eviction, or urgent caring responsibilities.

Relied on accountant who failed

LOW

Your agent let you down despite you providing information on time. HMRC is more sceptical of this — you remain responsible for your own tax affairs.

Excuses HMRC rejects

  • ✗I didn't know about the deadline
  • ✗I didn't know I needed to file a return
  • ✗I didn't receive a reminder from HMRC
  • ✗I was too busy
  • ✗I couldn't afford to pay my tax bill
  • ✗I found the process too complicated
  • ✗My accountant was too busy
  • ✗I forgot
  • ✗I didn't know I would be penalised

Have a reasonable excuse?

TaxFlip turns your excuse into a professional appeal letter that meets the Perrin v HMRC legal test — in 2 minutes.

Start Your Appeal — £4.99