How to document an Excel workflow so someone else can run it

The spreadsheet only one person understands

Almost every finance team has one. It works, the person who built it runs it every month, and nobody else is quite sure what the hidden tabs do. The risk shows up at the worst moment: a holiday during close, a resignation, or an auditor asking how a number was produced.

Documentation is the cheapest fix. It does not need to be long. It needs to answer the questions a new person would ask.

1. A workflow map

One page showing the sources, the steps and the outputs, in order. Name each export and the system it comes from, where it is saved, what the workbook does with it, and who receives the result. Mark the points where a person makes a judgment call.

2. A rules list

Every rule the workbook applies, written as a sentence a non-builder can check. For example: "A receipt matches an invoice when the reference and amount are identical." "Receipts with no reference are matched on customer and amount within five days, and held for review if more than one invoice qualifies." If a rule cannot be written as a sentence, it is probably a judgment call and should be routed to a person.

3. A check sheet

A list of the checks the workbook runs and what each status means, such as required columns, duplicates and agreement to the ledger. The seven close checks are a good starting set.

4. A change log

A simple table: date, what changed, why, who changed it and who approved it. This is the document most often missing and the one reviewers ask for first. It also stops the slow drift where small fixes pile up until nobody knows which version is right.

5. A one-page run guide

The steps for the person who runs it each month, written as a checklist: where to save the exports, what to refresh, which checks must pass, what to do if one fails, and where the output goes. Test it by asking someone who has never run the process to follow it while you watch without helping.

Where to keep it

Keep the rules list, check sheet and change log as tabs inside the workbook, so they travel with it. Keep the workflow map and run guide in the same folder as the exports. Documentation stored somewhere else tends to fall out of date.

What documentation does not do

Good documentation makes a workflow understandable and reviewable. It does not make the workflow correct, and it does not replace your auditor's own testing. What it does is make that testing faster, because the reviewer can see what the workbook is meant to do and compare it with what it does.