The spreadsheet is not the problem.
Excel is very effective for exploring, verifying, and reconciling information. It becomes fragile when no one knows exactly the meaning of a column, the source of an amount, or the rule applied to an exception.
Create a Minimal Contract
For each important data point, noting the name, format, source, owner, and expected control transforms a table into a transferable tool. This preparation serves both reporting and future interfacing.
To learn more. Prepare for electronic invoicing