A client — we're keeping the project anonymous here for privacy reasons — had a service contract with a single fixed monthly price. Sounds simple. It wasn't. Every month, the cost had to be split across two service areas based on actual hours worked, and that amount then divided proportionally across several legally separate companies that share the contract. Each company gets its own share, its own invoice.

That ran through a spreadsheet. Maintained by hand, every month.

When a wrong percentage isn't a typo, it's an accounting problem

In a normal cost estimate, a calculation error is annoying. Here it was something else: if the companies' distribution percentages didn't add up cleanly to 100% — and in a hand-maintained spreadsheet that was only a matter of time — one company got overcharged and another undercharged. Between related companies, that's not a minor slip, it's potentially a topic for the next tax audit. On top of that came an overtime clause: the hour quota in the contract was capped, and anything above it had to be caught and billed separately. Also tracked by hand, every single month.

The spreadsheet wasn't the problem because it was a spreadsheet. It was the problem because nothing in it automatically flags things when the numbers stop adding up.

The fix: calculate, validate, generate the invoice — in one step

We built the entire logic into a tool that takes the hours per service area and calculates the amount per company in seconds — including an automatic check that the distribution percentages actually total 100%, and automatic detection of overtime against the contractual quota. Errors that used to surface only at invoicing time, or later, now get caught at the calculation step itself.

From there it keeps going: from the calculated result, the tool creates ready-to-send invoice drafts directly in the accounting system at the push of a button — as drafts, not sent automatically, so a human still glances over them before anything goes out. Distribution breakdowns and hour-proof statements for each company go out by email in the same step. What used to be an end-of-month ritual involving a spreadsheet, a calculator, and a nagging feeling is now a process that runs in a couple of minutes.

Why this matters beyond this one case

Splitting costs across multiple companies, cost centers, or locations is one of those things almost no standard system handles cleanly, because every contract has its own rules. That's exactly why it nearly always ends up in the same place: a spreadsheet, maintained by one person who knows exactly what it means. Until that person is on holiday, or makes a typo, or the company grows and two entities become five.

That's almost always automatable without ripping out the accounting setup — it just takes someone to translate the calculation logic into code once and wire it into the right places.

If that sounds familiar, we've also collected a matching symptom on our solutions page — or just get in touch.