Use AI to draft budget-versus-actual commentary

Your monthly numbers are ready. Now you need to explain what changed, what you know about the reasons, and what needs attention.

AI can help organize those facts into a readable first draft. Your job is to check the calculations and make sure the explanation stays within the evidence. In this exercise, you will produce a short management commentary and a list of questions for the budget owners.

What you need

• A spreadsheet application or calculator to check the numbers.
• An AI chat tool that accepts pasted text. No file upload, programming, or paid feature is required by these instructions; access depends on your chosen service.
• Familiarity with revenue, operating costs, and operating profit.
• The synthetic data below. No company data is needed.

Hands-on time has not yet been measured in a reader pilot. The worked output is an editorial illustration, not a captured response from a named AI service. Your response will vary.

1. Start with a clear comparison

This fictional service business has completed September 2026. All amounts are in US dollars. Budget and actual cover the same month, accounts, and business scope. Expenses are positive amounts. Operating profit here means revenue less the five listed operating costs; tax, interest, and other items are outside this example.

The totals and profit are calculated rows, not extra accounts to add to the detail.

Two fictional supporting notes are available:

• N1 — Payroll: The finance team reconciled the USD 2,000 payroll overrun to approved temporary cover costs incurred in September.
• N2 — Contractors: The project owner confirmed that USD 4,000 of planned contractor work did not happen in September because a project was delayed. Its new delivery date and eventual cost are not confirmed.

There is no supporting explanation for revenue, marketing, software, or other operating costs. Do not fill those gaps with a plausible story.

For your own report, check the period, currency, account mapping, budget version, and completeness before asking AI to write. Use workplace information only through tools and data handling permitted by your organization.

2. Calculate before drafting

Use actual minus budget for the signed variance. Divide that difference by the budget for the percentage variance. All budget baselines in this example are positive.

Variance = Actual - Budget
Variance % = (Actual - Budget) / Budget * 100
Operating profit = Revenue - Total operating costs
Operating margin % = Operating profit / Revenue * 100

In a spreadsheet with budget in B2 and actual in C2, use =C2-B2 for the variance and =IF(B2=0,"N/A",(C2-B2)/B2) for the percentage, formatting the latter as a percentage. For negative budget baselines, agree a meaningful convention with your finance team rather than automatically interpreting this percentage formula.

For revenue and profit, a negative variance is unfavorable. For costs, a positive variance is unfavorable to current-period profit. A favorable cost variance does not automatically mean operational improvement.

Percentages are rounded to one decimal place; calculations use unrounded values. Budget operating margin is 20.0%; actual margin is 13.0%. The decrease is 7.0 percentage points when rounded to one decimal, not 7.0 percent.

Check the profit movement separately. Revenue contributes its variance; each expense contributes the negative of its variance:

20,000 - 8,000 - 2,000 + 4,000 - 2,000 - 500 + 500 = 12,000

Source: the synthetic data in this guide. The diagram summarizes the reconciliation; the line-by-line equation shows the offsets.

This is a comparison with a fixed budget. It cannot isolate price, volume, or efficiency effects without additional data. A flexed budget adjusts the expected result to actual activity; see ACCA’s explanation of flexible and flexed budgets. Our example lacks the activity and cost-behavior inputs needed for that analysis.

3. Ask AI to organize facts and gaps

Open a new conversation and paste this prompt. Replace the bracketed instructions with the tables and notes above before sending it.

Help me prepare September 2026 management commentary for a fictional
service business. All values are USD. This is a synthetic practice example.

INPUTS
[Paste the budget/actual table, checked variance table, and notes N1–N2 here.]

RULES
Use only these inputs. Treat notes as evidence only for the lines they address.
Signed variance is actual minus budget. Higher costs reduce profit.
Totals and operating profit are derived rows; do not double-count them.
Do not infer sales volume, prices, efficiency, permanent savings, or forecasts.
If a cause is missing, say it is unknown and propose a question to investigate.
Distinguish percentage changes from percentage-point changes in margin.

OUTPUT
1. A table: line, checked variance, profit effect, supported explanation,
   evidence reference, and follow-up question.
2. The bridge from budget profit to actual profit using each detail line once.
3. Any inconsistencies or missing information. Do not write commentary yet.

This gives the tool a bounded task and makes its evidence visible before you trust its prose. Compare its table with your calculations. If it cannot reconcile profit, stop and correct the inputs or calculations first.

An acceptable response should identify N1 as support for payroll, N2 as support for delayed contractor work, and the remaining causes as unknown. It should not call the contractor underspend a permanent saving.

4. Request a short draft

After checking and correcting the fact table, paste:

Using the corrected facts above, draft 120–160 words for a monthly management
report. Lead with operating profit versus budget. Explain the revenue gap and
offsetting cost movements. Attribute supported causes to N1 and N2, and state
where causes remain unknown. Include margin in percentage points.
End with practical follow-up questions. Do not invent owners, deadlines,
causes, savings, or forecasts. Use clear business language.

Here is an illustrative draft with deliberate review problems, written for this guide rather than captured from a service:

September profit was USD 12,000, down USD 8,000 against budget. Lower demand reduced revenue by 8%, while efficient contractor management saved USD 4,000. Total costs remained on budget, indicating good cost control. Margin declined by 7% to 13%. We should reduce marketing spend next month to recover profitability.

The numbers sound credible, but several statements go beyond the inputs. Lower demand is unproven. The contractor work was delayed, not shown to be more efficient. Net costs hide offsetting movements. The margin change uses the wrong unit. Cutting marketing is a recommendation unsupported by campaign results or commitments.

5. Review and revise

Use this checklist yourself; a second AI review can help surface issues but does not establish correctness.

Optional reviewer prompt:

Review the draft below against the original tables, formulas, and notes N1–N2.
[Paste the inputs and draft here if starting a new conversation.]
List each numeric error, unsupported causal claim, percentage-point error,
double-counted movement, and recommendation without evidence.
For every finding, cite the input or explain what evidence is missing.
Do not add new facts. Return findings first, then a corrected 120–160 word draft.

Checked editorial example (124 words; calculations reconciled, fictional notes preserved):

September operating profit was USD 12,000 versus a USD 20,000 budget, an unfavorable variance of USD 8,000 (40%). Revenue was USD 8,000 below budget (8%); its cause is not yet established. Total operating costs matched the USD 80,000 budget, but offsetting movements require attention. Payroll exceeded budget by USD 2,000 due to approved temporary cover (N1). Contractor costs were USD 4,000 below budget because planned work was delayed (N2); this is not confirmed as a permanent saving. Marketing and software overruns of USD 2,000 and USD 500 were partly offset by USD 500 lower other costs. Operating margin fell from 20.0% to 13.0%, a 7.0 percentage-point decrease. Follow up on revenue drivers, delayed work commitments, and the unexplained cost movements before proposing corrective actions.

Your wording can differ. The acceptance test is whether its numbers reconcile and every explanation has support.

Common problems and how to recover

• The tool invents a reason: Remove the claim, identify the missing evidence, and ask the relevant business team. A possible explanation belongs in a question, not in the reported facts.
• The percentages disagree: Check the denominator, period, and rounding. If budget is zero, show the absolute variance and mark the percentage N/A.
• “Costs are on budget” becomes the whole story: Show the offsetting detail. The zero net movement does not explain the individual accounts.
• A delay becomes a saving: Check commitments and expected completion. Do not extrapolate the current-period underspend into the forecast.
• The report becomes too long: Keep the profit result, principal movements, known explanations, and follow-ups. Retain the full reconciliation in supporting working papers.

Reuse the workflow

For the next month, replace the data and notes, calculate independently, and repeat the fact-table and draft steps. Agree review priorities with your manager; this example does not prescribe a universal materiality threshold. Record the budget version and the source of each explanation alongside your report.

As a second exercise, remove N2 and rerun the prompt. A defensible response should still report the USD 4,000 contractor underspend but say its cause is unknown. Try changing a budget line to zero and confirm that the percentage becomes N/A.

The supporting practice workbook contains these inputs, live calculations, and prompts. Its public download will be linked when the resource is released; the inline tables provide all the inputs needed to practice now.