It can prepare the workings, not make the choices. An AI agent can build a baseline from run-rates and contracts, collect and check department submissions, consolidate them and model scenarios. A budget, though, is a set of decisions about where money goes. Budget holders make their proposals, the finance director challenges them, and the board approves the result.
What part of budgeting is preparation?
A large share of budget season is assembly. Someone has to roll forward this period's costs, add contracted increases, apply the headcount plan, check that each department's spreadsheet adds up, chase the late ones and combine them into a single view. Then the same again for each revision.
An agent does this well. It can read existing contracts for price escalators, take headcount and pay data from the HR system, apply the payroll on-costs, and produce a baseline for each cost centre before the budget holders start. It can also check submissions for arithmetic errors, missing lines and assumptions that contradict each other. The collection process is set out in how to collect budget submissions from department heads.
What conditions make the agent's work useful?
- A clear timetable and template. The agent can enforce a structure; it cannot invent one.
- Sources for the baseline. Contracts, headcount and the prior period's actuals, each labelled with where it came from.
- Assumptions stated once. Inflation, pay increases, exchange rates and growth rates set centrally by finance, so the agent applies the same ones everywhere.
- Read-only access. The agent prepares workings; it does not change a submission without the owner's agreement.
What does the agent prepare, and who decides?
| Stage | Agent | People |
|---|---|---|
| Baseline | Builds run-rate, contracted and headcount costs per cost centre | Finance reviews |
| Submissions | Sends templates, chases, checks arithmetic and assumptions | Budget holders propose |
| Consolidation | Combines submissions, ties to the baseline, lists changes | Finance business partners challenge |
| Scenarios | Models effects of different growth or cost assumptions | Finance director chooses which to present |
| Board paper | Drafts tables and commentary on what changed | Finance director owns the paper |
| Approval | None | Board approves |
Where must the named approver sign off?
At the end, the board approves the budget; that sign-off is theirs alone. Before that, each budget holder signs their own submission and the finance director signs the consolidated version going to the board.
The separation that matters most is between proposing and challenging. A budget holder proposes. A finance business partner, who does not own the budget, tests the proposal against the baseline the agent built. If the agent drafted both the proposal and the challenge, nobody would actually be challenging anything.
One more boundary: an approved budget line is not approval to spend. The agent should never treat budget availability as authority to raise orders or pay invoices. Each payment still needs its own approval, which is the principle behind agents prepare payments and people release them.
An illustrative example
Take a charity with 12 departments. The agent builds a baseline for each from the prior period's actuals, the payroll file and contracts. It finds that the IT department's software contracts include price increases at renewal that nobody had noted, adding 48,000.
Eleven submissions arrive on time. The agent checks each and finds that the fundraising team has budgeted for three new posts but no recruitment costs or equipment, and that the facilities team used a different inflation figure from the one finance set. It sends each budget holder a specific query. The twelfth submission is late; the agent reminds the department head twice and escalates to the finance director.
The consolidated draft shows a deficit. The agent models two scenarios: delaying two of the new posts, and renegotiating the software renewals. The finance director takes both to the trustees, who approve the budget with the posts delayed.
What controls make it safe?
- Central assumptions. One set, versioned and applied everywhere.
- Owners sign their own lines. Every submission has a named budget holder.
- Independent challenge. Business partners, not the agent, test proposals.
- Board approval recorded. With the version approved.
- Budget is not spending authority. Kept separate in the agent's bounds.
The same discipline applies to the cost of running the agents themselves, covered in how to budget for running AI agents. Once the budget is approved, it feeds management accounts month by month. The wider controls are in AI agents for finance: books you can audit.
Questions people ask
Can the agent produce a zero-based budget?
It can list every cost with its contract, purpose and owner, which is the raw material for zero-based budgeting. Deciding what to keep is still the budget holders' job.
Can it reforecast during the year?
Yes, in the same way. It updates actuals, applies the agreed assumptions and drafts the reforecast for finance to review.
Does the agent see salaries to build the baseline?
It needs pay data to cost headcount. Scope its access to the budget work and record its reads, as for any sensitive data.