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OpEx variance walkthrough by department

Identify the three largest OpEx variances by department, classify each as one-off vs. structural, and propose a phasing adjustment.

Workflow · Variance Analysis | Role · Controller | Intermediate | 4 min | Updated 20260424
The prompt

Copy and customize

prompt.txt
You are a senior Controller producing the following deliverable: opex variance walkthrough by department.

Context
- Workflow: Variance Analysis
- Inputs available: {paste the data here}
- Period: {month / quarter}
- Audience: {who reads this}

What to produce
1. The headline takeaway in one sentence.
2. The three things that materially moved the result, with quantified contribution.
3. The one risk or anomaly worth flagging.
4. A short forward-looking note: what to watch next period.

Guardrails
- Use only the numbers provided; do not invent values.
- Cite a row reference for every claim.
- Flag anything you cannot reconcile rather than smoothing it over.
Open in
We’ll copy the prompt and open the chat.
How to use

Run it in four steps

  1. Pull departmental P&L vs. budget for the period, plus GL detail or accrual tags for the largest lines.
  2. Paste it into {paste the data here}, set {month / quarter}, and state your materiality threshold so the walkthrough ranks the right variances.
  3. Run it, then read each variance against the prior three months of trend to separate phasing from a real step-change.
  4. Confirm the one-off vs. structural call on the top three before you propose any phasing adjustment.
When to use

When to reach for this prompt

Use after the close pack is final and before the FP&A review with department heads. Pairs well with the headcount reconciliation — run that first if compensation is a major driver of the variance.
Example output

What you can expect back

Top 3 OpEx variances (Dept · $ vs budget · classification)

#DeptΔ vs budgetClassification
1Marketing+$240KStructural (Q2 paid media ramp)
2R&D+$185KOne-off (delayed contractor invoice)
3G&A-$95KStructural (T&E sustained low)

Phasing recommendation: Move $185K R&D contractor accrual into next month; underpace G&A budget by $70K next quarter.

Limitations · Worth knowing

This prompt has real limitations you should understand.

Classification of one-off vs. structural is judgment-driven. If you don't tag accruals in the GL, the prompt will mis-classify late vendor invoices as structural. Always sanity-check the top three with the budget owner before sending out.
01

Accruals masquerade as structural

A late vendor invoice booked in the current month looks identical to a structural cost increase. Without accrual tags in the GL, the model classifies both as "structural" — and the budget owner gets a phasing recommendation that's wrong by a month.

02

Allocations move silently

Shared-services allocations that shift between departments mid-period surface as variances that have nothing to do with the budget owner. The prompt will rank them anyway, and the dept head will spend the review explaining what they did not do.

03

T&E is lumpy by design

Sales-team T&E spikes in months with QBRs, training, or onsites. A "structural" classification from a single month of data is meaningless — but the prompt will not flag the seasonality unless you feed it prior years.

Prerequisites

What your data needs to look like

  • P&L by department vs. budget for the period
  • GL detail or accrual tags for the largest line items
  • A standing definition of "material" (e.g. >$50K or >5%)
  • Prior three months of trend for phasing context
See it run on real data

See how FinanceOS handles this prompt on real financial data.

Book a 20-minute walkthrough. We’ll run this exact prompt against a sample dataset reconciled through FinanceOS, and show you what changes when the data underneath is right.

Book a walkthrough
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