Let’s cut straight to the chase: DATEV is the backbone of German tax advisory. Over 40,000 firms work with it daily. But let’s be honest: DATEV is not a system that makes automation easy. Closed interfaces, proprietary formats, a software architecture that in many parts still dates back to a time when “cloud” was a weather phenomenon.
Yet something fundamental has changed in the past two years. With DATEVconnect Online, the DATEV Export Interface, and CSV import capabilities, there are now real connection points. And with workflow engines like n8n, you can build genuine automation from these — without having to overhaul your entire firm’s IT infrastructure.
At Exasync, we work together with our partner UXUIX on exactly these kinds of projects. Not in theory, but in production, at real firms with real clients. This article shows you three concrete scenarios that work, what they cost, and where the limitations are.
DATEVconnect Online is the central programming interface that DATEV has been providing for several years. It allows external applications to exchange posting data, document images, and master data with the DATEV data center. At its core, this works via a REST API with OAuth 2.0 authentication.
Specifically, through DATEVconnect Online you can:
What DATEVconnect Online cannot do: Map the business logic of accounting. The interface transports data — it doesn’t verify account assignments, it doesn’t generate financial statements, and it doesn’t replace a tax advisor. This is important to understand before diving into automation projects.
Besides DATEVconnect Online, there’s the DATEV Export Interface (formerly ASCII export). It’s frequently underestimated but extremely useful for batch processes: You can export posting batches, master data, and account labels as structured files and process them in other systems. The format is documented and stable.
And then there’s CSV import into various DATEV modules. It sounds old-fashioned but in practice is often the fastest way to get data into DATEV — especially for firms that haven’t activated DATEVconnect Online yet or for modules that don’t (yet) offer an API.
n8n is an open-source workflow engine that fundamentally differs from Zapier and Make. The most important distinction for tax firms: n8n can run self-hosted. Your client data never leaves your own server. This isn’t just a nice-to-have — for tax-related data, it’s a mandatory requirement for many firms.
On top of that, n8n has an HTTP Request node that can literally call any REST API. DATEVconnect Online, Lexoffice, sevdesk, FastBill, ELSTER — anything with an API can be connected. n8n also supports code nodes (JavaScript or Python), which let you parse proprietary formats — such as DATEV exports with their specific field delimiters and character sets.
Exasync uses n8n productively in two variants: As a cloud instance at our partner UXUIX for client projects, and as a self-hosted installation for internal workflows. Both variants run reliably. The cloud variant has the advantage of lower maintenance, the self-hosted variant the advantage of full data control.
For a detailed platform comparison, I recommend our article n8n vs. Zapier vs. Make. Here’s just the bottom line: For the DATEV context, n8n is the better choice because it can run on-premise and brings the flexibility needed for proprietary interfaces.
This is the workflow with the biggest impact. In a typical tax firm, the process looks like this: The client sends a document via email or uploads it to DATEV Unternehmen Online. A clerk opens the document, identifies the supplier, assigns the invoice to the correct client, assigns it to the right account, and creates the posting record in DATEV Kanzlei-Rechnungswesen.
This takes 3 to 8 minutes per document. For a firm with 200 clients and an average of 50 incoming invoices per client per month, that’s 10,000 documents monthly. Even if only half are automatable, we’re talking about 250 to 670 hours of time savings per month.
Here’s what the n8n workflow looks like:
The trigger is an IMAP node that monitors a defined mailbox — for example, documents@firm-example.com. As soon as a new email with a PDF attachment arrives, a code node extracts the attachment and passes it to an OCR service. We typically use the Mindee node or the Google Document AI API — both can be connected directly in n8n.
The OCR returns the extracted text. Another code node parses out the relevant fields: invoice number, gross/net amount, VAT rate, IBAN, supplier name, invoice date. Then the matching happens: An HTTP Request node queries the creditor list of the client via DATEVconnect Online. If the supplier is recognized by name or IBAN, the assignment is clear.
In the next step, the workflow generates a posting record in DATEV format: debit account (from the creditor’s default account), credit account (payables), amount, document date, posting text. This posting record is written to the client’s document batch via DATEVconnect Online. Simultaneously, the document image is uploaded and linked to the posting record.
The final node sends a summary to the responsible clerk: “14 documents processed automatically, 3 documents for manual review.” The three open documents are typically those with unknown suppliers or poor scan quality.
Important: The workflow doesn’t replace professional review. It handles the assignment and preliminary account coding — the approval of the posting record remains with the tax advisor or clerk. This isn’t a technical limitation but a deliberate decision: Whoever bears responsibility for the accounting must have the final say.
Every firm knows this problem: Client master data exists in at least three systems simultaneously. In DATEV, in the firm’s software (RA-MICRO, Advolux, AnNoText), in the CRM, and often in an Excel spreadsheet too. When a client changes their address, it gets updated in one system and forgotten in the others. After three months, you have four different addresses for the same client.
The n8n workflow for master data sync:
The trigger is a Cron node that starts the workflow daily at 6:00 AM — before the firm opens. The first step: An HTTP Request node fetches the current client list with all master data (name, address, tax number, bank details, contact person) via DATEVconnect Online.
In parallel, a second HTTP Request node reads the master data from the secondary system — such as the CRM. Then comes the core logic: A code node compares the records field by field. Same client number but different address? That gets flagged as a discrepancy. New client in the CRM that doesn’t exist in DATEV yet? Gets flagged as “to be created.”
The workflow generates three outputs: First, a list of automatically synchronized changes (e.g., phone number updates that were applied in DATEV). Second, a list of discrepancies that need manual review (e.g., if a company name has changed — rebrand or typo?). Third, a summary: “347 clients checked, 12 changes synchronized, 3 conflicts for resolution.”
The result is sent via Slack message or email to firm management. Time savings: 4 to 8 hours per week that were previously spent on manual reconciliation. And most importantly: no more outdated data in correspondence.
Deadlines are existential in tax law. Filing deadline for VAT returns, appeal deadlines, deadlines for annual financial statements, retention period deadlines. A missed deadline can cost the client money — and the firm its professional liability insurance.
Most firms manage their deadline monitoring in DATEV Eigenorganisation comfort or in separate tools. This works in principle, but the external connection is missing: automatic reminders to the client, escalation when there’s no response, integration with project management.
The n8n workflow for deadline monitoring:
Two triggers work in parallel. The first is a Cron node that checks the deadline list daily each morning. It reads all open deadlines with due dates and client assignments via DATEVconnect Online (or via CSV export from DATEV Eigenorganisation). A code node calculates the remaining time and categorizes: Green (more than 14 days), Yellow (7 to 14 days), Red (under 7 days), Critical (under 3 days).
Depending on the category, the following happens: For Yellow, the responsible clerk receives a reminder. For Red, the client additionally gets a message — via email with a specific request for which documents are still missing. For Critical, firm management is notified and an escalation task is created in project management.
The second trigger is a webhook: When the client uploads the requested documents (via email or client portal), the workflow automatically detects this, updates the deadline status, and sends a confirmation to the clerk.
The result: No clerk has to manually go through the deadline list each morning. No client gets forgotten. And firm management always has an overview of how many deadlines are currently at Yellow or Red status.
Transparency about costs is important to us, so here’s a realistic calculation for a mid-sized firm with 150 to 300 clients:
Setup costs (one-time):
Ongoing costs:
Savings:
At an internal hourly rate of EUR 45 (clerk level), that translates to EUR 990 to EUR 1,710 per month. The ongoing costs of EUR 100 to EUR 350 pay for themselves three to ten times over. The one-time setup costs are recovered within 2 to 6 months.
Not all DATEV modules offer an API. DATEV Kanzlei-Rechnungswesen, DATEV Eigenorganisation comfort, DATEV Lohn und Gehalt — many desktop applications simply have no programming interface. The software runs locally, the data sits in the DATEV data center, and in between is a proprietary connection that’s invisible to external tools.
This is exactly where Power Automate for Desktop comes in. It’s Microsoft’s RPA tool (Robotic Process Automation) that simulates human inputs on the desktop: mouse clicks, keyboard entries, menu navigation. It sounds like a workaround — and it is. But a working workaround beats an elegant solution that doesn’t exist.
In practice, it looks like this: n8n orchestrates the overall process. When a step requires a DATEV desktop application, n8n calls a Power Automate flow via webhook that runs on the firm’s computer. The Power Automate flow opens DATEV, navigates to the correct client, performs the desired action (e.g., start export, retrieve deadline list), and returns the result to n8n.
At Exasync, we use Power Automate for Desktop for exactly these cases. It works reliably but has limitations: The computer must be powered on and logged in. The DATEV interface shouldn’t change too drastically between updates (otherwise the click paths break). And execution is slower than an API call — an RPA run takes seconds to minutes, where an API call takes milliseconds.
Our advice: Use RPA where no API exists, and DATEVconnect Online everywhere it’s available. The combination of both covers the majority of all firm processes.
This is the question missing from most automation articles — and the most honest one you can ask. Here’s the clear answer:
Professional judgment: Whether a business transaction is deductible as a business expense, whether a situation falls under Section 4 Paragraph 5 of the Income Tax Act, whether an invoice meets the requirements of Section 14 of the VAT Act — this requires tax expertise and judgment. No workflow in the world can replace that. Automation delivers the data and assigns it. The assessment stays with the tax advisor.
Client advisory: When a client calls and asks whether they should restructure their GmbH into a holding company, no n8n workflow will help. Advisory requires empathy, experience, and the ability to read between the lines. That’s the core of tax advisory — and the reason why tax advisors won’t be replaced by software.
Initial setup: Every new client has individual account assignments, specific posting rules, and special requirements. You can’t automate the first month — you have to understand the rules before you can pour them into a workflow. From the second month onward, automation kicks in.
Edge cases: Partial payments, credit notes, reversal invoices, documents in foreign currencies, intra-community deliveries with special regulations — all of these are cases that the workflow marks as “not automatically processable” and routes to the clerk. Good automation knows where it needs to stop.
If you’ve read this far, you’re probably facing a concrete situation: Your firm processes thousands of documents per month, your clerks are stretched thin, and you’re wondering whether automation is realistic or just another IT project that fizzles out.
My suggestion: Start with one workflow. Not three. Document processing is the best entry point because it has the biggest impact and the results are immediately measurable. Plan for 4 to 6 weeks for setup and testing. After the first month in production, you’ll know whether automation works for your firm.
What you need for that:
If you’re generally interested in the topic of automating accounting, we’ve written a dedicated article about it. For a broader look at process automation beyond accounting, I recommend our guide on automating business processes.
And if you’d rather speak directly with someone who’s done this before: Get in touch. Exasync and UXUIX advise tax firms on implementation. No slide deck, no strategy paper. Just an honest assessment of what’s automatable in your situation, what it costs, and how long it takes. Because in the end, it’s not about technology. It’s about your clerks spending their time on what they’re trained for: professionally sound work instead of mindlessly typing document numbers.
