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First drafts of HMRC penalty appeal letters for tax advisers

Draft the structure and wording of a penalty appeal from facts you supply, with ChatGPT, Claude or Gemini. Free to about £20 a month.

At a glance

  • What it costsFree–£20 a month

  • Worth, in extra profit or time saved in the worked example£107 a month

  • Pays for itselfIn a few days

  • Sign up and configure; no technical skills neededEasy to set up

Figures come from the worked example below, using its stated assumptions. Tool prices checked . How we check prices

The problem

A late filing or late payment penalty can be appealed on a reasonable excuse, and each appeal letter takes careful drafting. If you handle 8 a month at 45 minutes each, that's 360 minutes, 6 hours a month.

What the AI does

Write down the facts of the case yourself, leaving out the client's name, UTR, NI number and address. Ask ChatGPT, Claude or Gemini to turn them into a clear, polite appeal letter, using the structure you prefer. Then replace the placeholders with the real details, check each fact against the file and HMRC's guidance on reasonable excuse, and send. The assistant must never add facts you haven't given.

A worked example

A tax practice in Cardiff deals with about 8 penalty appeals a month. The adviser drafts the facts in bullets, asks an assistant for a letter, checks it against the file and sends it.

Before

45 minutes to draft each of 8 letters: 6 hours a month

After

About 25 minutes to prompt, check and finish: 3.3 hours a month

What it's worth

About 2.7 hours a month saved (20 minutes x 8 letters = 160 minutes), worth around £107 if your time is worth £40 an hour. Cost is free to about £20 a month for one person; free plans have usage limits.

How to set it up

  1. Write the facts and the dates from the file, without names, UTRs or addresses.
  2. Ask ChatGPT, Claude or Gemini for a letter in your house style that uses only those facts.
  3. Check every statement against the file and HMRC's guidance on reasonable excuse before finalising.
  4. Add the real details yourself and have the client confirm the facts if the letter says what they did.
  5. Note the appeal time limit from the penalty notice in your primary diary before you send.

What goes wrong

  • An assistant can invent a plausible excuse. Anything you send HMRC must be true and from the file; check every sentence.
  • The time limit to appeal is on the penalty notice. Record it in your primary diary; the assistant doesn't track it.
  • Never paste identifiers into a consumer AI plan. Add them after.
  • A weak case dressed up in good writing still loses. Decide whether there is a reasonable excuse before you draft.

More ideas for Tax Advisers

Plain-English tax explainer letters for tax advisers

Build reusable letters explaining payments on account, tax bills and record keeping with ChatGPT, Claude or Gemini. Free to about £20 a month.

  • Costs Free–£20/mo
  • Worth £200/mo
  • Pays for itself in a few days
  • Easy to set up

Tax return approvals signed online with TaxCalc eSign

Send tax returns for online signing with reminders and an audit trail. 250 envelopes £245; needs TaxCalc return software, priced separately.

  • Costs £20/mo
  • Worth £70/mo
  • Pays for itself in about two weeks
  • Some setup needed

Last updated 17 October 2026.