As of 13 August 2026, AI can only partly build a zero-based budget for your business.

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 1 hour until you can act on the result.

   How to actually do it

   1. Open your accounting or banking software and export the relevant historical transactions, recurring bills, supplier commitments, payroll totals, current cash balance and available revenue information into CSV or spreadsheet files.
   2. Open the exports and add a source column, a VAT basis column where known, and a note for each item that is personal, one-off, duplicated, uncertain or not part of the budget period.
   3. Write down the budget period, minimum cash target, business priorities, known commitments and spending constraints, then separate figures that are VAT-inclusive from figures that are VAT-exclusive.
   4. Paste the prompt into an AI chat or upload the prepared files to a spreadsheet AI tool, replacing every bracketed slot and asking it to mark missing or uncertain figures instead of filling them in.
   5. Copy the resulting budget into Excel or Google Sheets and check each monthly total, category total, variance and closing cash balance against the source exports using spreadsheet formulas.
   6. Compare payroll, VAT, tax, rent, finance payments, subscriptions and supplier commitments against the current records and correct any timing, duplication or VAT classification error.
   7. Ask the AI to regenerate the budget using only the corrected figures, then send the assumptions and unresolved decisions to your accountant or bookkeeper before approving material spending.

   Prompt

   Build a zero-based operating budget for my UK business from the data I provide below. A zero-based budget must justify every planned cost rather than carrying forward last year's budget.
   
   Business type: [business type]
   Budget period: [start month and year] to [end month and year]
   Currency: GBP
   VAT basis: [VAT-inclusive, VAT-exclusive, or explain which figures use each basis]
   Cash target or minimum cash balance: [amount or target]
   Business priorities for this period: [priorities]
   Known constraints: [constraints]
   
   Use only the figures and facts in the data below. Do not invent revenue, costs, tax rates, VAT treatment, payroll costs, supplier commitments or growth assumptions. If a required figure is missing, mark it as MISSING and state what is needed.
   
   Create:
   1. A monthly budget with income, payroll, premises, software, suppliers, marketing, insurance, professional fees, taxes and other relevant categories.
   2. A line-by-line explanation of why each planned cost is included, its source, whether it is fixed or variable, and whether it is essential, discretionary or a one-off.
   3. A monthly cash movement and closing cash balance, clearly separating cash timing from accounting timing where the data allows.
   4. A list of assumptions, exclusions, uncertain classifications and figures that need confirmation.
   5. A comparison of the budget with the supplied historical or planned figures, showing variances in pounds and percentage where the comparison is valid.
   6. Three scenarios labelled conservative, base and upside, but only create scenario figures where the supplied data supports them. Otherwise mark the scenario as unavailable.
   7. A short list of decisions I need to make before approving the budget.
   
   Keep VAT, payroll and tax items separate. Do not give tax or accounting advice, and do not state that any cost is deductible or that a filing is correct. Show all calculations so I can check them. Return tables that can be copied into Excel or Google Sheets, followed by the assumptions and checks.
   
   Data:
   [paste bank transaction summary, accounting export, payroll totals, supplier commitments, recurring bills, planned purchases, revenue information, cash balance and other relevant records here]

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