From a fragmented invoicing puzzle to one basis ready for the bookkeepers

The challenge

A Danish consultancy with around 40 consultants had a familiar problem. Invoicing took hours per client because the underlying data was spread across five systems. Terms were agreed by email, contracts sat on shared drives, client details lived in the business register, mileage was logged in Excel sheets and distances were looked up by hand in Google Maps or Rome2Rio. That did not just waste time, it meant under-invoicing. Consultants forgot to log visits, mixed up mileage rates, and the bookkeepers spent extra days every month putting the puzzle together. Worst of all, some invoices were never sent.

The solution

During a two-day hackathon the team built an automated invoicing workflow that pulls data from all five sources: Outlook for emails with agreed terms, shared drives for contracts, virk.dk and proff.dk for business register data, Google Maps for the mileage between consultant and client, and the internal timesheet system. The workflow gathers everything per client and period, validates it against the agreed terms, and delivers an invoicing basis ready for bookkeeping in exactly the format the company's accounting system expects. Invoicing time is down 85 percent, no visits are forgotten, and the bookkeepers get a data set they can trust.

How we built it

1. 1

   Mapping the data sources

   We went through each consultant's month-end routine and mapped exactly where the data lived, which fields were missing and what was filled in by hand on a hit-and-miss basis.

2. 2

   Integrations per source

   n8n workflows connected to Microsoft 365 (email and drives), virk.dk and proff.dk, Google Maps and the internal timesheet system. Each source is versioned, so a change in one place does not break the chain.

3. 3

   Consolidation per client

   Claude reads contracts and emails with agreed terms and extracts, for each client, the hourly rate, mileage rate, invoicing frequency and any special arrangements. Everything is stored as structured data so it can be reused.

4. 4

   Validation and exception handling

   The workflow compares logged visits with the contract terms and flags exceptions, such as visits with no agreement behind them, to the consultant before the invoice goes out.

5. 5

   Delivery to the bookkeepers

   Exported in the format the accounting system expects (CSV with specific columns), ready to import with one click. The bookkeepers approved the format before it went live.

What we learned

• →The biggest return came from catching forgotten invoices, not from saving time. The automation revealed a significant amount of under-invoicing.
• →Consultants only accept a new system if it removes work rather than adding it. We built only to take work away, never to add reporting.
• →Validation is worth its weight in gold. The automatic exception flags are now also used as evidence when client agreements are renegotiated.
• →The bookkeepers are the most important stakeholders to involve from day one. They know exactly which format works.