Case study · Fiduciary & administrative services · French-speaking Switzerland

A real engagement, client anonymised. Figures measured with the client and rounded; not audited by a third party.

A 35-person fiduciary firm now invoices in 3 days instead of 12

An AI assistant connected to the accounting software, mailbox and documents prepares entries, invoices and reminders; a person approves every outgoing action. Results measured over 90 days.

Scope and limitations

Rounded figures, measured on the trial scope and then the extended scope. A real engagement: the client’s name and any detail that would identify it have been removed.

Engagement summary01 / 04
Company
Fiduciary and administrative services, around 35 people, 3 legal entities
Scope
Around 450 active client files: documents, invoicing, reminders and approvals
Software in place
Swiss accounting software, Microsoft 365, partial document filing, email used as the to-do list
Starting point
No AI tool in use; individual use of ChatGPT with no rules
Duration6 months
Period2025–2026
TeamNumezis (advice and development) + 2 client-side leads

The back office was absorbing the growth: every new client file meant more data entry, filing, reminders and cross-checks between the three entities. Process knowledge sat with two people, and invoices regularly went out late.

Management had received several vendor offers promising turnkey “AI automation”. None answered the practical questions: where does our clients’ data go, who approves an accounting entry before it is posted, what happens when the AI gets it wrong?

The question asked

Buy yet another piece of software, or add an AI assistant on top of the software already in place, with a person approving every outgoing action?
01

Sensitive fiduciary data

Financial and personal data of around 450 clients, covered by the Swiss data protection act and professional secrecy. No data could be used to train a vendor’s models.

02

No in-house IT person

The system had to run without anyone technical on site: simple handling, clear alerts, a written procedure for outages.

03

An SME budget

An investment the partners could defend, committed in stages, each one approved on measured results.

04

French and German

Documents and correspondence in both languages, often mixed within a single file.

What we put in place

We replaced no software. The assistant reads incoming email, documents and accounting entries, prepares actions and acts only within written limits: role-based access rights, human approval before anything is sent, a log of every operation.

The building blocks

Admin assistantSorts incoming email and documents, prepares entries, reminders and draft replies for approval
Connections to your softwareControlled access to the accounting software, document filing and mailbox, each with its own access rights
Search across your documentsFinds information file by file, without mixing entities or clients
Human approvalEvery entry, email and reminder goes through a person, with adjustable thresholds
Operations logEvery read, proposal and decision is recorded and available to the external auditor
Fixed rulesVAT, due dates and charts of accounts stay as programmed, checkable rules — never an AI estimate
01

Analysis and starting measurement 3 weeks

Mapping of the real processes, measurement of handling times and invoicing delays, sorting of sensitive data, choice of the first scope.

02

Set-up 6 weeks

Access rights, read-only connections, a test environment with anonymised files, operations log.

03

Supervised trial 8 weeks

The assistant works for one of the three entities; every action is approved by a person; weekly error review and threshold tuning.

04

Extension 6 weeks

Roll-out to all three entities, sample checks for low-risk actions, team training.

05

Security review and handover 3 weeks

Operating procedures, alerts, security review; management takes over the monthly check-in.

Safeguards6
  • Nothing sent without human approval during the first 3 months
  • Data kept separate by entity and by client file
  • Models used with no retention and no training on client data
  • When in doubt, the assistant holds back and passes the file to a person
  • Tamper-proof operations log, reviewed with the external audit firm
  • Monthly check-in with management: errors, costs, decisions to extend

Measured results

The first three weeks were used to measure the starting situation. The figures below compare the 90 days before the trial with the last 90 days of the engagement, on the same scope.

BeforeAfter
Median time to issue an invoice12 days3 days
Handling time per incoming client file~45 min18–25 mindepending on complexity
Data-entry errors found at auditstart−70%on the trial scope
Client reminders sent on time~60%>95%
Staff concerned using it every week—9 of 12after 90 days

Rounded figures, measured on the trial scope and then the extended scope. A real engagement: the client’s name and any detail that would identify it have been removed.

Every study also says what could have been done better.

  1. 01

    Measure from the first week. We consolidated the starting measurement during the analysis; six weeks of finer data would have made the final comparison stronger.

  2. 02

    Bring in the external auditor at set-up. Their review of the log during the trial validated the approach; earlier, it would have saved two rounds of rework on the log format.

  3. 03

    Build fewer connections at the start. Four were delivered; two were enough for the trial. The other two should have waited for proof of use.