As of 13 August 2026, AI can calculate VAT on a UK supplier invoice.

What to actually do

1. Hand it to a person

   The route this page recommends

   A person who owns the outcome does this end to end, worth it when the failure is dear.

2. Use a tool built for this

   Second choice

3. Do it yourself

   The distant third

   A chat interface, chat-fluent skill, and roughly 30 minutes until you can act on the result.

   How to actually do it

   1. Open the supplier invoice and make sure the supplier name, invoice date, invoice number, currency, line amounts, VAT rate and VAT amount are readable.
   2. Check whether the invoice states reverse charge, zero-rating, exemption, mixed VAT rates, or any other special treatment, and note that wording exactly.
   3. Paste the invoice text or attach the invoice to a chatbot, then add the copyable prompt and provide any known VAT rate or internal accounting instruction.
   4. Compare the model's extracted net, VAT and gross figures with the original invoice, including each line and each VAT rate.
   5. Recalculate net plus VAT with a calculator or spreadsheet and check that the model has not treated a foreign-currency amount or reverse-charge invoice as an ordinary UK VAT charge.
   6. Ask your bookkeeper or accountant to resolve every flagged treatment or discrepancy, then enter the confirmed figures and VAT code in your accounting system.

   Prompt

   Calculate the VAT on this UK supplier invoice. Use only the information supplied below and do not invent missing figures. Extract the supplier name, invoice date, invoice number, currency, net amount, VAT amount, gross amount, VAT rate or rates, and whether the invoice states reverse charge or another special treatment. If the invoice already shows VAT, check its arithmetic rather than replacing it silently. If VAT is missing, calculate it only when the applicable rate is explicitly provided or clearly stated on the invoice. Show the calculation for each line or VAT rate, reconcile net plus VAT to gross, and flag any discrepancy, unreadable field, mixed rate, foreign currency issue, reverse charge, or question about whether the invoice is valid for a VAT reclaim. Do not decide that VAT is reclaimable and do not give professional advice. End with a short list of facts that I must confirm with our bookkeeper or accountant before posting it.
   
   Invoice details or extracted text:
   [PASTE INVOICE TEXT OR ATTACH THE INVOICE]
   
   Known VAT rate or accounting instruction, if any:
   [PASTE RATE OR INSTRUCTION, OR WRITE 'NOT KNOWN']

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