Microsoft 365 Copilot · Accounting team
Guardrail Card
William Kim
Staff Accountant · Automation Lead
williamckim.com/copilot
01 · The split Copilot is not the reconciliation engine
Deterministic tools FIND
- Power Query merges
- INDEX/MATCH
- SUMIFS
- Pivot tables
- Conditional formatting
Same input always returns the same answer. Completeness is provable:
totals tie or they do not. This is what belongs in the workpaper.
Copilot EXPLAINS
- Classifying an exception list
- Searching email and Teams for why an item is open
- Writing the matching logic you then run yourself
- Drafting the narrative and the follow-up
- Reviewing a finished rec for gaps
Judgment, context, and language. Never arithmetic, and never the
matching itself.
Never ask Copilot to be the matching engine. "It found 12 unmatched items
when there were 15" is an audit finding, not a productivity win.
02 · The 20 second prompt R-STAR-QC, compressed
Act as [role]. Here is [context]. Do [one task].
Return [exact format]. Do not [the thing that would ruin it].
That last sentence is the accuracy control, not politeness. Giving the
model permission to say "I don't know" is the cheapest accuracy gain available.
03 · The four non-negotiables Before anyone signs
- Every number that reaches a workpaper ties back to a control total before anyone signs it. Copilot drafts. The accountant ties out and signs.
- Every categorized exception needs a source document, not just a plausible story.
- If Copilot names a dollar amount you did not give it, that is a red flag, not a finding.
- Note in the workpaper where AI assisted. Reviewers should know what to scrutinize.
The data rule
Company financial data stays in M365 Copilot.
No exceptions, and no personal accounts.