As of 13 August 2026, AI cannot file your UK corporation 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 gets you a draft, but you cannot verify it yourself. That is the catch.

   How to actually do it

   1. Open the relevant HMRC corporation tax guidance and your company's accounting records, including the final accounts, trial balance, fixed asset records, payroll information and details of transactions needing tax treatment.
   2. Confirm the company's accounting period, UTR, registered details and filing status from HMRC or Companies House records, then keep those details in a separate working document.
   3. Paste the prompt and the relevant figures or extracts into a chatbot without including unnecessary personal data, and ask it to produce the missing-information list and CT600 mapping only.
   4. Compare every mapped figure and arithmetic check against the signed accounts, trial balance and source records, marking anything that does not reconcile as CHECK.
   5. Send the working papers, unresolved CHECK items and the chatbot's questions to a UK accountant or tax adviser for confirmation of the tax treatment and the final computation.
   6. Use UK corporation tax filing software or ask the professional to enter and submit the confirmed return to HMRC, then retain the submitted return, computation and supporting records.

   Prompt

   I need to prepare a UK corporation tax return for [company name] for the accounting period [start date] to [end date]. Do not file anything, make a tax election, choose a relief, invent a figure or give professional advice. Using only the records and HMRC material I provide, create: 1. a list of information and documents still missing, 2. a table mapping each supplied figure to the relevant part of the CT600 or corporation tax computation, 3. a separate list of figures or tax treatments that require confirmation by a UK accountant or tax adviser, 4. arithmetic checks that can be performed from the supplied figures, and 5. a plain list of questions to ask the professional before submission. Mark every unsupported, ambiguous or inferred item as CHECK. Quote the source document and page or section for each factual mapping where possible. If the supplied records are insufficient, say so rather than completing the return.

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