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AI Invoicing and Time Tracking: Build a Reviewable Workflow
Short answer
An AI agent for service invoices sets the recorded working time against the contract terms, points out hours not assigned to a project and prepares a draft bill for the manager to approve. Issuing the invoice in the e-invoicing system (KSeF in Poland) is a separate stage after approval. The agent costs from €3,000 net at Syntalith and, with 150 client bills a month at 30 minutes each, pays back in 1.6 months.
How we workDetails ↓
- 01Call30 minutes with an engineer, free
- 02PrototypeA working system on your process and data, free
- 03ImplementationTarget and fixed price in the contract; 50% at signing
- 04Acceptance50% once the agreed target is met
- net per agent for one process, build paid once
- from €3,000
- from signing the contract to acceptance
- 6–16 weeks
- free prototype on your cases
- €0
We belong to the OpenAI and Anthropic partner programmes and learn through their official courses. What this means ↓
Author: Syntalith · 3 min read
Statistics
Invoices and AI: statistics 2026
1.6 mo.
payback of a €3,000 agent with 150 client bills a month: €2,618 of work today, €795 with checking and the model. Scenario.
1 July 2030
According to the European Commission (2025), digital reporting based on e-invoices applies to cross-border B2B transactions in the EU from 1 July 2030.
Source: European Commission, VAT in the Digital Age (ViDA) (2025) ↗
−87%
According to Anthropic (2025), AI cuts the time of a task on invoices, memos and other documents by an estimated 87%.
Source: Anthropic, Estimating AI productivity gains (2025) ↗
14–56%
According to Anthropic (2025), controlled trials found smaller time savings, from 14% to 56%.
Source: Anthropic, Estimating AI productivity gains (2025) ↗
30.7%
According to Eurostat (2025), 30.7% of EU enterprises paid for cloud software for finance and accounting.
Source: Eurostat, Digital economy and society statistics, enterprises (2025) ↗
Figures checked: 22 October 2026
Where working time gets lost
A service company bills clients by the hour. At the end of the month the project manager exports time from the timer, compares it with the contract, looks for hours entered against the wrong project and asks the team about tasks without a description. Some work never reaches the bill because nobody assigned it, and some reaches the wrong client. The invoice goes out several days late.
The agent sets recorded time against the contract: rates, hour limits and scope. It points out entries without a project, hours over the limit and tasks outside the scope, with a question to the person who entered them. It prepares a draft bill with a list of lines and the source of each. The manager approves a specific version: if even one line changes after approval, the draft goes back for approval.
- Every line has a source: a time entry, a task, the contract
- Hours over the limit and outside the scope wait for the manager's decision
- Approval applies to a specific version of the draft
- The invoice in the e-invoicing system (KSeF in Poland) is created only after approval, in the accounting process
Billing a client for a service and assessing an employee are different purposes. The agent does not assess anyone's performance. Annex III to the AI Act lists monitoring and evaluating the behaviour of employees among high-risk uses, and analysing a team's communication needs a clear description of scope and, according to UODO, Poland's data protection authority, often a data protection impact assessment.
What it costs and when it pays back
- Today
- 150 client bills × 30 min = 75 h (€2,618)
- With the system, a person checks the output in 30% of the time
- €785
- Model, 2 calls per case, Claude Sonnet 5.5
- €9
- Cost of one case
- €17.45 today, €5.30 with the system
- Saving
- €1,823 a month
Payback of €3,000
1.6 months
The volume, the time and the checking share are the scenario's assumptions. €34.90 an hour is the EU average hourly labour cost for 2025 according to Eurostat. Model: 10,000 input and 1,500 output tokens per call at Anthropic's rates, converted at the ECB rate of 1.1205 USD per euro on 22 October 2026.
The count covers the work around a case: searching, reading, writing and passing things on. What remains is the time to check the output, 30% of today's work in the scenario. Before the quote we measure both times on 20 to 100 cases the team has already handled, in a €0 test that takes 5 working days.
When a timer and an export are enough
If the team reliably assigns time to projects and contracts have a simple hourly rate, an export from the timer to an invoice template is enough. An agent makes sense when contracts have limits, fixed fees and scopes, time entries are incomplete, and the manager searches email and messenger every month for missing information.
A simple rate, reliable time entries
an export from the timer to an invoice template
no build
A few clients a month
the manager bills by hand
no build
Dozens of clients, limits and fixed fees, incomplete entries
an agent that prepares the bills
from €3,000
Where to start
The first scope covers one team's bills for one month, compared with the bills prepared by hand. We build this as part of AI agents. For the free process review, a description of one case from recent weeks and the tools it ran through is enough. You do not need to send confidential documents, and you get a written plan within 2 working days.
Worked example · Scenario
How we count the payback: AI in a service company
We run the same count for your billing in the free process review.
€4,363
a month for handling 1,500 job emails
Payback: 0.8 mo.
5 minutes to read an email and reply and checking in 15% of the old time are our assumptions. €34.90 an hour is the EU average hourly labour cost for 2025 according to Eurostat, for companies with 10 or more employees. Model cost: Claude Sonnet 5.5, about 3,000 + 600 tokens per message with a draft reply, at the ECB rate of 1.1205 USD per euro on 22 October 2026.
See the full calculation →
