Month-end close pack with Claude Cowork

TL;DR. At the end of every month, assemble the close pack — trial balance, key reconciliations, variance commentary, leadership 1-pager — without finance rebuilding the same Excel from scratch each cycle. Eight to twelve hours per close saved at steady state.

Job to be done#

Assemble the month-end close pack: trial balance, key reconciliations, variance commentary, and a one-page leadership summary, with consistent structure across cycles so packs compare cleanly month over month.

Who runs it#

Controller, FP&A lead, or external accountant working on a recurring engagement.

Inputs (inbox/)#

• Trial balance export from the accounting system (CSV or Excel)
• Bank statement exports
• Subledger exports (AR aging, AP aging)
• Last month's pack from archive/ for comparability
• Budget vs actual reference data

Outputs (output/)#

• A close pack folder containing: balance sheet, P&L, cash summary, AR aging, AP aging, key reconciliations, variance commentary, leadership 1-pager.
• All in .xlsx with a single .docx for the narrative.
• Consistent file naming so packs across months compare cleanly.

Prompt seed#

Read the trial balance in /inbox/tb-[month].xlsx and last month's pack
in /archive/close-[prev-month].
Build the close pack in /output/close-[month] following the structure in /CLAUDE.md.
Run the standard reconciliations between TB and bank/AR/AP.
Flag balance differences over £500 with a "Reconciling" tab.
Generate variance commentary against /inbox/budget-[year].xlsx
with one paragraph per material driver.
Plan the run before producing files.

Quality bar#

• Numerical accuracy is non-negotiable. Verify every number is a formula reference, not a paste.
• Variance threshold (e.g., £500 or 5%) is explicit in CLAUDE.md.
• Narrative tone matches house style — no marketing language.
• Common trip-up: Cowork sometimes invents account names. Pin the chart of accounts via CLAUDE.md.

Time saved (typical)#

8–12 hours per close at steady state. Higher in the first cycle while the prompt is being tuned.

Upgrade path#

• Convert to a monthly-close skill once two clean cycles run.
• Add a connector to the accounting system to skip the export step.
• Schedule the variance commentary refresh on day 5 of the month — see Scheduled tasks.

Tinkso's take#

The leadership 1-pager is the part that lands hardest. Prompt for "what would the CFO want on a single page" and you will get bullet salad; prompt for "three numbers that moved, why each moved, one decision the CFO needs to make" and you will get a useful page. The structure is the work.

Try this#

Run the seed prompt against the last closed month. Compare to the pack you actually produced. The diffs are the rules you have not written into CLAUDE.md yet — add them and run again.