Tax Appeals 2026/27 — HMRC Reviews & Deadlines

If you disagree with an HMRC penalty or direct-tax decision, you normally appeal to HMRC first and can then request a statutory review before appealing to the First-tier Tribunal. Many appeals turn on the facts, the notice and the evidence; a reasonable excuse is assessed against the circumstances and what you did once the problem ended. Check the deadline calendar in the Self Assessment Deadlines guide and model penalties with the HMRC Penalty Calculator→.

This guide covers the appeal route step by step, the deadlines at each stage, reasonable excuse, and the penalty scale you are appealing against.

The Appeal Route and Deadlines

If you miss a deadline, explain the reason and ask HMRC to accept the late appeal; the notice and the relevant appeal rules determine whether an extension is available. A statutory review is handled by a different HMRC review officer and normally takes 45 days, with the officer contacting you if it will take longer. If the review upholds or varies the decision, you usually have 30 days from the review result letter to appeal to the tax tribunal.

Reasonable Excuse — What Works and What Does Not

The test is objective: would a reasonable person in your circumstances have been able to meet the obligation, and did you act reasonably once the problem arose? Evidence decides every case — a GP letter, a death certificate, a screenshot of HMRC's own system error, proof of posting. An accountant's error is a weak excuse because HMRC holds you responsible for your agent, though incorrect advice you reasonably relied on can carry some weight. Note the distinction: lack of funds is not an excuse for late filing, but it is a reason to arrange a Time to Pay agreement rather than appeal.

Real Appeal Examples

Example 1 — Hospital stay, late filing: Sarah's 2025/26 online return was due 31 January 2027. She was admitted for emergency surgery on 5 January and filed on 28 February — 28 days late. The initial late-filing penalty is generally £100; daily penalties do not start until the return is more than three months late. Her appeal attaches medical evidence and explains that she filed as soon as she was able; HMRC assesses whether the reasonable-excuse conditions are met.

Example 2 — HMRC system failure, late payment: James attempts to pay his £5,000 bill before the due date, but an HMRC system failure prevents completion and he pays as soon as access returns. A 5% late-payment penalty is normally tested at 30 days after the payment due date, not merely because a payment arrived a few days late. Screenshots and bank records may support a reasonable-excuse appeal, but HMRC decides the facts.

Example 3 — Bereavement: Maria, sole executor, misses a filing deadline after a close relative dies. A death certificate and a clear timeline may support a reasonable-excuse appeal, but neither a particular cancellation nor a particular penalty total is automatic.

The Penalty Scale You Are Appealing

The late filing regime escalates: £100 immediately, £10 a day for up to 90 days after three months, then a 6-month and 12-month penalty generally based on 5% of the tax or £300, whichever is greater; higher behavioural penalties can apply in some cases. Inaccuracy penalties depend on behaviour and disclosure, so do not use one percentage for every error. Keep the notice, the date it arrived, and supporting evidence from day one.

Time to Pay — An Alternative

If you owe tax but cannot pay on time, a Time to Pay (TTP) arrangement may spread the bill subject to HMRC’s agreement and affordability checks. It does not automatically cancel every late-payment penalty; the timing of the arrangement and whether its terms are met matter. You can discuss payment support while separately appealing a penalty, keeping the underlying tax and the disputed penalty distinct.

Free Help and Escalation

You do not need a professional to appeal most penalties. TaxAid gives free advice to people on low incomes and can review your appeal letter before you send it; Tax Help for Older People covers the over-60s; and the Citizens Advice tax clinics help with basic disputes. If HMRC's handling of your case is genuinely poor — long delays, lost paperwork, unreasonable demands — the Adjudicator's Office investigates complaints about HMRC's service, and a finding against HMRC often softens the penalty position even when the underlying decision stands. Your MP can raise the case with HMRC's customer team as a last resort. None of these replace the formal route, but a second pair of eyes before you file can turn a weak appeal into a strong one.

Writing an Effective Appeal Letter

Your letter is your best chance, so structure it like a professional submission. Open with your name, address, Unique Taxpayer Reference and the penalty notice reference, then state plainly that you are appealing. Next, set out the background: the return or payment in question and the deadline you missed. Then give the reason for the failure in factual, chronological terms — "I was admitted to hospital on 5 January and discharged on 15 February; my GP letter is attached" — rather than emotional language. Explain why that reason is a reasonable excuse by reference to what a reasonable person in your position would have done, and list the evidence: medical letters, death certificates, screenshots, proof of posting. Close by requesting cancellation of the penalty and asking HMRC to confirm in writing. One page is usually enough; two pages of justification beat five pages of complaint, and attaching evidence beats asserting it.

Frequently Asked Questions

Evidence and decision checks

A reliable tax appeals 2026 27 review starts by fixing the tax year and the date on which the relevant event happened. Record the person's or business's status, the income or transaction category, the amount before tax, tax already withheld, and any election or claim being relied on. Do not combine a headline figure with a final liability: the result can change when another income source, a payment date, an ownership interest or a qualifying condition is added.

Keep the source documents behind every important input. Depending on the subject, that may include payslips, invoices, bank statements, contracts, provider statements, travel records, HMRC notices, payroll submissions, valuations or correspondence. Where an amount is apportioned, write down the method and retain the underlying total. If a correction is made, preserve the original figure and explain the reason, date and evidence for the replacement.

Before relying on the result, check the current official guidance for the same tax year and jurisdiction. Distinguish enacted law from a consultation, draft measure, announcement or future proposal, and record the effective date. Reconcile the final estimate to the relevant return, payroll record or HMRC account. A calculator or explanatory guide can support a decision, but it cannot replace the eligibility test or the official filing and payment process.

Evidence and decision checks

A reliable tax appeals 2026 27 review starts by fixing the tax year and the date on which the relevant event happened. Record the person's or business's status, the income or transaction category, the amount before tax, tax already withheld, and any election or claim being relied on. Do not combine a headline figure with a final liability: the result can change when another income source, a payment date, an ownership interest or a qualifying condition is added.

Keep the source documents behind every important input. Depending on the subject, that may include payslips, invoices, bank statements, contracts, provider statements, travel records, HMRC notices, payroll submissions, valuations or correspondence. Where an amount is apportioned, write down the method and retain the underlying total. If a correction is made, preserve the original figure and explain the reason, date and evidence for the replacement.

Before relying on the result, check the current official guidance for the same tax year and jurisdiction. Distinguish enacted law from a consultation, draft measure, announcement or future proposal, and record the effective date. Reconcile the final estimate to the relevant return, payroll record or HMRC account. A calculator or explanatory guide can support a decision, but it cannot replace the eligibility test or the official filing and payment process.

Avoid the penalties in the first place by knowing the filing dates in the Self Assessment Deadlines guide, and check the penalty maths with the HMRC Penalty Calculator→.

Official sources

• GOV.UK — Review of a tax or penalty decision
• GOV.UK — Self Assessment penalties
• GOV.UK — Pay a Self Assessment penalty
• GOV.UK — Tax appeals, reasonable excuse and tribunal guidance