Check your HMRC online account first. If the return for that year is not shown as received, it is still outstanding, and the filing obligation remains yours even though you paid someone to send it. Get the return filed as soon as you can, because late-filing penalties increase the longer a return stays outstanding.
Then keep three issues apart: filing the overdue return, any appeal against the penalties, and any complaint or fee dispute with the accountant. They involve different people, different deadlines and different evidence, and progress on one does not pause the others.
Check Whether HMRC Received the Return
Sign in to your personal tax account, which HMRC says you can use to submit, view or manage a Self Assessment return. Check the tax year concerned for a received return and its date, and save a dated screenshot of what you see.
A PDF of the completed return, a tax calculation or an email saying the work is done does not prove that HMRC received anything. Ask the accountant for the submission acknowledgement for that year. A late-filing penalty notice for the year is also a strong sign that HMRC had no return by the deadline, so keep the notice and its issue date.
Gather the Engagement Letter and Messages
Before you contact the accountant again, save the original files and emails that show what was agreed and what happened.
- The engagement letter or terms, showing which returns and tax years the accountant agreed to prepare and submit.
- Dates you sent records, and any requests the accountant made for further information.
- Your approval of the return, if you gave one, and any message telling you it had been filed.
- Your reminders or chasers, and the replies you received.
- Invoices, payments and any notice that the accountant was stopping work or closing the practice.
- HMRC letters and penalty notices for the year, with their issue dates.
A new accountant, an appeal and any complaint will all rely on this pack. Write a short dated timeline while events are fresh, marking uncertain dates as approximate.
Moving to a New Accountant Without Sharing Your Login
Never give an accountant, old or new, your HMRC sign-in details. HMRC's guidance on how to change or remove your tax agent's authorisation says you must not give your sign-in credentials to your agent or anyone else. The new accountant should request authorisation through HMRC's agent process. HMRC says a new authorisation replaces any existing one, and you can also remove an old agent through your online account.
Ask the previous accountant in writing for your records and any work in progress. While you wait, the new accountant can often start from your bank statements and your own copies. A late tax return filing engagement should begin by confirming which years are outstanding and which records are missing.
Choose the replacement with care. HMRC's guide to choosing a tax agent warns that anyone can call themselves a tax agent, that they need no qualifications, and that HMRC does not regulate agents. Check any professional-body membership the firm claims, and compare written quotes on the same scope.
Registration rules for advisers are also changing. HMRC began rolling out mandatory tax adviser registration on 18 May 2026, in stages running to 31 March 2027, for advisers paid to deal with HMRC for clients. HMRC's policy paper says taxpayers may be affected if an adviser can no longer act for them because the adviser cannot meet the new requirements or is sanctioned. If your accountant says they cannot act for you any more, treat that as the point to appoint someone else rather than waiting.
Is Relying on Your Accountant a Reasonable Excuse?
Sometimes, but not automatically. HMRC's reasonable excuse examples include one that fits this situation: "you relied on someone else to send your return, and they did not". The law adds a condition. Under Schedule 55 to the Finance Act 2009, relying on another person is not a reasonable excuse unless you took reasonable care to avoid the failure.
HMRC's manual on reliance on another person explains what it looks for. It expects you to have told the other person what you needed, set deadlines, checked progress regularly and reminded them where appropriate. You should be able to say what you did and, normally, why the failure happened. Once the excuse ends, you must put things right without unreasonable delay.
The same page cites a 2012 tribunal decision that distinguished an accountant acting as your agent from one giving professional advice. Where the accountant was simply meant to send the return, their default usually leaves you little room to argue. HMRC also lists situations where reliance may give rise to an excuse, including the agent's illness or bereavement and delays in getting paperwork from a previous adviser after you engaged a new one.
Your evidence of reasonable care carries the appeal, not the accountant's failure on its own. You usually have 30 days from the date a penalty was issued to appeal, and a late appeal needs a reason. When you prepare the SA370 appeal form, set out the facts in date order. HMRC decides whether to cancel a penalty, and no adviser can promise that it will.
Keeping a Penalty Appeal Separate From a Complaint
An appeal asks HMRC whether you owe the penalty. It does not deal with the accountant's fees or any loss you have suffered, so a complaint, a fee dispute or a compensation claim runs on a separate track with the accountant. Start by complaining to the firm in writing and keep its reply.
If the accountant belongs to a professional body, that body may consider a complaint about conduct, but each one sets limits.
- ICAEW asks you to raise the issue with the firm in writing and allow at least 28 days first. It cannot investigate fee disputes or contractual disagreements and has no general compensation scheme.
- ACCA may refer a complaint to its conciliation service where resolving it with the firm has failed.
- AAT does not investigate fee disputes, says a complaint is not a substitute for seeking compensation through the courts, and normally considers complaints raised within a year.
- Complaints about CIOT and ATT members go to the Taxation Disciplinary Board, and none of the three gets involved in fee disputes.
Because anyone can call themselves a tax agent, your accountant may belong to no professional body at all. In that case your complaint goes to the firm, and recovering money is a legal question for independent advice. Do not let a complaint hold up the overdue return or a penalty appeal deadline.
A Recovery Checklist
- 1Check your HMRC account for each affected tax year and save a dated screenshot.
- 2Save the engagement letter, messages, invoices and HMRC notices, then write a short timeline.
- 3Authorise a new agent through HMRC's process, remove the old one if needed, and never share your sign-in details.
- 4Get the overdue return prepared, checked by you and filed.
- 5Note each penalty notice date and decide whether to appeal within 30 days, using your evidence of reasonable care.
- 6Raise any complaint or fee dispute with the old accountant in writing, separately from HMRC.
Our penalty appeals service can review the notices and your evidence alongside a separate quote for the filing work, so you know what the evidence supports before deciding whether to appeal.