As of 13 August 2026, AI can only partly check your Self Assessment tax return.

What to actually do

1. Hand it to a person

   The route this page recommends

   Someone with a licence or accountable authority has to sign this before it counts.

2. Use a tool built for this

   Second choice

3. Do it yourself

   The distant third

   A chat interface, chat-fluent skill, and roughly 2 hours until you can act on the result.

   How to actually do it

   1. Open the current Self Assessment guidance and relevant tax return notes on GOV.UK, then save the pages that apply to your tax year and income types.
   2. Gather your P60 or P45, employment income records, bank and investment statements, invoices, business expense records, pension records, Gift Aid records and any earlier payments on account that relate to the return.
   3. Create one spreadsheet with a separate row for each income or expense item, including its date, amount, category, source document and whether it has already appeared elsewhere.
   4. Enter the draft return figures and the spreadsheet totals into the prompt, attaching documents only after removing unnecessary account numbers, National Insurance numbers and other private details.
   5. Ask the chatbot to produce the reconciliation table, discrepancies, missing evidence and unresolved tax-treatment questions using the copyable prompt.
   6. Compare every figure in the response with the original records and independently recalculate the spreadsheet totals, then compare any tax-treatment point with the saved GOV.UK guidance.
   7. Send the draft return, evidence list and unresolved questions to an accountant or tax adviser for the points involving reliefs, business expenses, residency, property income, foreign income or other judgement calls.
   8. Make only evidenced changes, complete HMRC's own checks, and submit the return yourself or through the professional who has agreed to file it.

   Prompt

   Check this draft UK Self Assessment tax return as a reviewer, not as the person filing it. Use only the information and documents I provide, and do not invent figures, dates, expenses, income, reliefs or explanations. Reconcile each income and expense figure to the supplied records, check the arithmetic, identify duplicated or missing entries, and list every assumption. For each possible tax treatment or relief, say whether it is supported by the supplied evidence, whether it needs checking against current GOV.UK guidance, or whether a qualified UK tax adviser should decide it. Do not tell me to claim anything merely because it might apply. Do not submit the return or present your review as professional advice. Produce: 1) a table of each return section with the supplied figure, supporting document, arithmetic check and result; 2) a list of discrepancies and missing evidence; 3) questions I must answer; 4) items I must verify on current GOV.UK; 5) items an accountant or tax adviser should check; and 6) a short list of changes to make before filing. Return: [paste the draft return or section figures]. Records and documents: [paste or attach them]. Tax year: [insert tax year]. Personal circumstances relevant to the return: [insert only relevant facts].

   Open it prefilled in ChatGPT or Claude, or copy it into Gemini, which takes no prefill link.