As of 13 August 2026, AI cannot apply the correct tax code to an employee.

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 employee's payroll record and gather the current tax code, pay frequency, employment start date and any recorded benefits or pension information.
   2. Open the employee's P45 or completed starter checklist and the latest HMRC coding notice, removing unnecessary personal data before sharing copies.
   3. Paste the documents and the payroll facts into the prompt, keeping the source of each fact labelled.
   4. Ask the chatbot to compare the current payroll code with the HMRC notice and produce the evidence and discrepancy table requested in the prompt.
   5. Check that every fact in the chatbot's table appears in the supplied documents and delete any conclusion based on an assumption or missing document.
   6. Send the flagged discrepancies and source documents to your payroll professional or contact HMRC through the appropriate employer route before changing the code.
   7. Apply the confirmed code in your payroll system, record the source and date of the confirmation, and retain the review for the payroll audit trail.

   Prompt

   You are helping an employer review a UK PAYE tax-code change. This is not professional advice. Do not make a final decision or invent any facts. Use only the documents and facts pasted below.
   
   Employee details:
   [employee name or reference, without unnecessary personal data]
   [employment start date]
   [pay frequency]
   [known benefits, pension arrangements or other relevant payroll facts]
   
   Documents and notices:
   [P45 or starter checklist]
   [current HMRC coding notice]
   [previous tax code]
   [latest payroll record]
   [any employee-provided explanation of a change]
   
   Produce a table with these columns: source, relevant fact, possible effect on the tax code, and missing information. Compare the current code with the supplied HMRC notice and identify any discrepancy. State clearly whether the documents support applying the code, whether the case must be held for clarification, or whether it must be referred to HMRC or a qualified payroll professional. Do not calculate tax, guess an emergency or standard code, infer facts from incomplete documents, or advise me to override an HMRC notice. List the exact evidence a payroll professional should check before any code is entered into payroll. If the documents conflict, identify the conflict and do not resolve it yourself.

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