What is a DATEV API integration and when is it worth building?
A DATEV API integration is software that moves bookkeeping data from your own systems into DATEV, the accounting platform most German tax advisers use, without manual exports. It is worth building once someone in your office spends hours each month preparing data your Steuerberater then corrects anyway.
The pattern is familiar across the Mittelstand. Orders come from a shop, invoices from a CRM, payouts from a payment provider, and receipts pile up in an inbox. Every month an employee exports a few files, renames columns, fixes dates and emails everything to the Kanzlei. The adviser imports it, finds wrong accounts or missing receipts, and sends questions back. Nobody enjoys the loop.
A good DATEV API integration replaces that loop with a repeatable job: the same rules applied to every transaction, receipts attached automatically, and errors flagged before the data leaves your system rather than after your adviser finds them.
The word “API” is used loosely here. DATEV accepts data in two broad ways: structured files in the DATEV-Format, and online interfaces called data services. Both count as integration, and the right choice depends on your volume and on what your adviser prefers. The next sections explain both.
EXTF file export or DATEV online API: which route fits your business?
Choose the EXTF file route when a monthly or weekly batch is enough and you want to start quickly; choose the online route when data should flow continuously, receipts must be linked automatically, or you are building a product that many DATEV users will connect to.
The file route uses the DATEV-Format, a CSV interface for importing data into DATEV Rechnungswesen. According to DATEV’s developer portal, it can be imported manually in DATEV’s accounting program, automatically on a local machine through DATEV’s console tool, or through the DATEV data centre with the online API accounting:extf-files. No developer-portal onboarding is needed just to produce a correct file.
The online route uses DATEV data services: APIs in DATEV’s data centre with user authentication through OAuth 2.0 and OpenID Connect. Examples on the portal include the Buchungsdatenservice for bookings, master data and document images, the Rechnungsdatenservice 1.0 for invoices and document images into DATEV Unternehmen online, and the Belegbilderservice for scanned and digital receipts.
Decision rule
Under a few thousand bookings a month, one or two sources, and an adviser who is happy to import a file: start with EXTF. Several live channels, receipt linking, or a commercial product: plan the online route.
An EXTF booking batch is a semicolon-separated CSV file whose name starts with EXTF_, with a metadata header on line one, column names on line two and one booking per line from line three. Getting the header right is half the battle.
DATEV’s format description sets strict technical rules: fields separated by semicolons, every line ending in CR/LF, text fields in quotation marks with inner quotes doubled, no line breaks inside fields, and a comma as the decimal separator for amounts. The header line carries the format version, the data category (the Buchungsstapel uses category 21), the adviser number, the client number, the fiscal-year start and the length of general-ledger account numbers.
Two details catch many first attempts. The account length in the header must match how the client is configured in DATEV, or the import fails. And the default character set is ISO-8859-1 or code page 1252; DATEV can read UTF-8 only with a byte-order mark, and only through manual import or the accounting:extf-files API, not through the local console tool. German umlauts in customer names are exactly where that goes wrong.
There is also a volume limit: DATEV states that one booking-batch file can hold up to 99,999 bookings. High-volume shops split exports by period or channel. DATEV offers a free checking program for DATEV-Format files, and we run exports through it before your adviser ever sees them.
How do you get access to the DATEV online APIs?
You register on the DATEV developer portal, create an organisation and an app, subscribe to the API you need, build against the sandbox, then request production approval from DATEV. It is a formal process, and it applies to every integration.
The portal’s FAQ explains the steps. An organisation is required before you can create an app, and several members can share it. Subscribing to an online API gives sandbox access. Moving to production is requested on the app page, after which DATEV’s consulting team schedules an appointment to check and approve the solution; there is no rollback from production to sandbox. DATEV also says there is no simplified path for companies that only want to use an integration internally: the same standard onboarding applies.
Costs sit with DATEV as well. The portal lists a one-off onboarding fee that includes a few hours of DATEV consultation, running charges per API call depending on the plan, and the need for a DATEV test system, which you can own, share with another DATEV customer, or buy. We factor that into planning so the online route is chosen for real benefits, not by default.
One recommendation from DATEV matters for ownership: the commissioning company should create its own organisation on the portal, stay its owner and invite the service provider’s developers as members. That is exactly how we work.
DATEV API integration for Shopify, Shopware and WooCommerce
In a shop-based DATEV API integration, data reaches DATEV best when orders, refunds, fees and payouts are booked separately and then reconciled, rather than exporting only the order list. Each platform exposes that data differently, but the booking logic is the same.
On Shopify, a small app reads orders, refunds and transactions through the Admin API and builds the batch outside the store. On Shopware, a plugin or scheduled job reads order and document data inside your installation. On WooCommerce, a plugin hooks into orders and refunds, and payment-provider reports are imported alongside. Marketplace channels such as Amazon usually arrive as settlement reports that need their own mapping.
What your Steuerberater really wants is traceability: every booking should carry a document number that matches an invoice or credit note, and every payout from a payment provider should reconcile to the orders it contains, minus fees. We build that reconciliation step because it is where manual work hides.
Existing connector apps cover many standard shops, and for a simple store they may be enough. The DATEV API integration becomes custom work when you combine several channels, sell B2B with net terms, handle foreign VAT, or need receipts linked automatically.
Uploading receipts and invoices to DATEV Unternehmen online
Receipts belong next to their bookings, and DATEV offers dedicated online interfaces for sending document images to DATEV Unternehmen online. Automating that step saves more time than most businesses expect.
According to DATEV’s developer portal, the Belegbilderservice transmits scanned and digital documents from an app or partner solution to DATEV Unternehmen online automatically, while the Rechnungsdatenservice 1.0 exchanges document images and structured invoice data between ERP cloud solutions and DATEV Unternehmen online. There is also an XML-based, UTF-8 interface for importing invoice and cash data into DATEV Unternehmen online.
In practice, we collect outgoing invoices from your shop or CRM and incoming supplier invoices from a mailbox, name them consistently, and send them through the relevant service with the document number that also appears in the booking. Your adviser opens a booking and sees the receipt, no emailing back and forth.
Structured e-invoices make this easier still: an XRechnung or ZUGFeRD file already contains the data a booking needs. Our e-invoicing page explains how incoming files are read and validated before they reach DATEV.
Agreeing SKR03 or SKR04 account mapping with your Steuerberater
In any DATEV API integration, the account mapping is the tax adviser’s decision, not the developer’s. We ask your Steuerberater which standard chart (SKR03 or SKR04) the client uses and which account and tax key each transaction type should hit, then encode those answers exactly.
SKR03 and SKR04 are DATEV’s two most common standard charts of accounts; the same sale lands on a different account number depending on which one your business uses. That is why we never copy a mapping from another project. We prepare a mapping sheet that lists every transaction type we find in your data and leave the account and tax columns for your adviser to fill in.
- Domestic sales at the standard and reduced VAT rates
- Sales to EU business customers with a VAT ID, and to EU consumers
- Sales outside the EU
- Shipping charges, discounts, vouchers and gift cards
- Marketplace and payment-provider fees
- Refunds, partial refunds and chargebacks
- Payouts and transfers between clearing accounts and the bank
Once the sheet is signed off, it becomes a configuration file in your repository. When your adviser changes a rule next year, updating one line is enough, and the change history shows who changed what and when.
Lexware Office and sevDesk: lighter alternatives to a full DATEV API integration
If you do your own bookkeeping in a cloud tool and your adviser works from its exports, connecting to that tool can be simpler than connecting to DATEV directly. Lexware Office and sevDesk both offer public APIs for this.
The Lexware API documentation describes a REST API for the product formerly called lexoffice, authenticated with a bearer API key the user generates, with endpoints for invoices, vouchers, contacts, credit notes and files, and a limit of two requests per second. It also lists XRechnung and ZUGFeRD support. sevDesk likewise provides an API for connecting outside systems.
The trade-off is control. A cloud bookkeeping tool handles the accounting logic and its own export to your adviser, so your integration only needs to create invoices, vouchers and contacts correctly. A direct DATEV API integration puts the booking logic in your code, which makes sense when volumes are higher or your adviser wants data straight in DATEV.
We build either. The rate limit alone is a planning point: a shop with thousands of daily orders needs queuing and batching to stay under two requests per second.
How much does a DATEV API integration cost?
With us, a scheduled DATEV-Format export starts at US$600, and custom connectors using DATEV’s online APIs, several channels or receipt upload start at US$900. DATEV’s own onboarding and usage fees, if you take the online route, are paid to DATEV separately.
Quotes on the market vary widely, and the spread is explained by scope rather than by the file format. The questions that move the price: how many sources feed the bookings; how many special cases your adviser wants booked separately; whether payouts must be reconciled against orders; whether receipts are uploaded and linked; and whether the online route is needed, with its sandbox, approval appointment and test system.
A narrow first phase is often the smart buy. Start with an EXTF export for your main shop, run it for two months with your adviser, then add channels and receipt upload once the mapping is proven.
How long does a DATEV integration project take?
A single-source DATEV API integration based on an EXTF export usually takes two to four weeks, most of it spent on mapping and a test import with your adviser. An online API connector with several sources and receipt upload typically needs six to nine weeks, depending on how quickly DATEV’s production approval appointment can be scheduled.
Weeks 1–2
Transaction inventory from your real data, mapping sheet sent to your adviser, header values (adviser number, client number, fiscal year, account length) confirmed.
Weeks 2–4
Export built and checked with DATEV’s format checker; your adviser imports a test month and compares it with their own bookings.
Weeks 4–7 (online route)
Developer-portal app, sandbox build, receipt upload and error handling; production approval requested from DATEV.
Weeks 7–9
Production switch, one full month of parallel checking, documentation and handover.
Data protection and hosting for your DATEV connection
Booking data contains names, addresses and payment details, so a DATEV API integration should run on your infrastructure, store credentials securely and keep only what it needs. That is how we build it.
The connector runs on your server or cloud account, ideally in an EU region. OAuth tokens and API keys sit in a secret store, not in code. Logs record what was sent and when, without copying full customer records. Temporary export files are deleted after successful delivery, and access for our developers is personal, logged and revocable.
Under GDPR you remain the controller of your customers’ data, and your privacy notice and any processing agreements are your lawyer’s area. Our job is to make the technical side match what they decide. For the website side of the same topic, see our GDPR-compliant website guide.
What goes wrong in DATEV integrations, and how to avoid it
In a DATEV API integration, most failures come from mapping and encoding, not from code. Wrong accounts, a mismatched account length and broken umlauts cause the majority of rejected or corrected imports.
- A developer who picks account numbers without asking the Steuerberater.
- Exports that ignore refunds, fees or payouts, leaving the bank account unreconciled.
- UTF-8 files without a byte-order mark sent through a route that expects code page 1252.
- Document numbers in bookings that do not match any receipt.
- A developer-portal organisation owned by the provider rather than by you.
- No test import with the adviser before the first live month.
- Batches above the 99,999-booking limit sent as one file.
We ask for one real month of data early, run a test import with your adviser, and fix every difference before switching on automation.
Building a DATEV API integration with a freelance team in India
A remote DATEV API integration works well because the job is specification-driven and remote by nature: files, APIs and a test system, with your adviser as the business expert. Our day runs three and a half to four and a half hours ahead of Germany, so we share your late morning and afternoon for calls.
Communication is in English. DATEV field names, SKR terminology and your adviser’s notes stay in German, and we work with them directly; if a nuance matters, we ask rather than guess. WhatsApp messages are answered seven days a week.
Money and paperwork: you get an itemised quote in USD, approve it in writing, and pay in USD or EUR by Wise or bank wire. Invoices are issued from India; how you treat them for VAT is a question for your accountant. General terms are on our terms page.
Your first fortnight with us: a kick-off call with you and, ideally, your adviser; read access to one month of shop or CRM data; a transaction inventory and draft mapping sheet by day five; and a first DATEV-Format test file, passed through DATEV’s checker, by the end of week two.
Worked example: a hypothetical Shopify and B2B wholesaler
Imagine a coffee roaster in Freiburg, invented for illustration, selling to consumers on Shopify and to cafés on invoice from a small CRM. Today an office manager spends two days a month preparing files for the Steuerberater.
Discovery would show four sources: Shopify orders, Shopify payouts, CRM invoices with 14-day terms, and supplier invoices arriving by email. The adviser uses SKR03 and wants consumer sales split by VAT rate, café sales on customer accounts, and payment fees booked separately.
Phase one: a weekly EXTF batch combining Shopify and CRM data, reconciled payouts and matching document numbers, checked with DATEV’s tool and test-imported by the adviser. Budget from US$600. Phase two, a quarter later if phase one works: receipt upload to DATEV Unternehmen online and automatic reading of supplier e-invoices, as custom software from US$900.
The office manager’s two days would shrink to reviewing an exception list. This scenario is illustrative only; your data will look different, and the quote will follow what discovery actually finds.
DATEV API integration checklist
Use this before you ask anyone to quote your DATEV API integration, and again before go-live. It keeps the project small and your adviser involved.
- List every system that creates sales, fees, refunds or payouts.
- Ask your Steuerberater for the chart (SKR03/SKR04), adviser number, client number and account length.
- Decide: file route, online route, or a cloud bookkeeping tool in between.
- For the online route, create your own developer-portal organisation and invite the developers.
- Collect one real month of data for testing.
- Get the mapping sheet completed and signed by your adviser.
- Run DATEV’s format checker and one test import before going live.
- Agree who watches error alerts and who fixes rejected bookings.
Automation, AI and where a DATEV connection fits in your wider stack
A DATEV API integration is often the first automation a business trusts, and it sets up others. Once transactions are clean and mapped, the same data can feed dashboards, cash-flow forecasts or an AI assistant that answers “which customers are overdue?” from your own records.
We keep AI out of the booking logic itself: accounts and tax keys follow your adviser’s fixed rules. AI helps around the edges, for example proposing fields from a supplier PDF that has no structured data, always for a person to confirm. Such automations start at US$600.
Planning a broader automation roadmap? Our AI automation page covers what else is worth automating in a German Mittelstand business, and what is not.