DATEV API: access and routes into DATEV

Data reaches DATEV in three ways: as a posting batch (Buchungsstapel) file in DATEV format (EXTF), as receipts in DATEV Unternehmen online, or through the online APIs from the DATEV developer portal. For the online APIs, the application must be registered with DATEV and pass a review. The tax advisor must approve the matching data services for the client.

Many companies search for "DATEV API" and expect a key that lets any program write postings straight into DATEV. It does not work like that. DATEV is built around cooperation between companies and tax advisors. Anyone who wants to deliver data uses one of the intended routes. Which one fits depends on who does the bookkeeping and how often data flows.

What routes into DATEV are there?

1. Posting batch in DATEV format (EXTF file)

The most common route. Your system generates a CSV file in DATEV format. The file name starts with EXTF_, the first line is a header record with details on advisor, client and fiscal year, and the postings follow. Such a posting batch (Buchungsstapel) is imported in DATEV Rechnungswesen (accounting) through batch processing, and according to the DATEV help also in Kanzlei-Rechnungswesen.

Advantage: your system needs no approval from DATEV for this. Disadvantage: someone has to hand over and import the file, and errors only show up during the import.

2. Receipts to DATEV Unternehmen online

Invoices and other receipts can be uploaded to DATEV Unternehmen online, where the tax advisor matches them to the postings. For automatic transfer, the DATEV developer portal lists a dedicated online API for receipts (accounting:documents). It transfers receipts into the Belege online area. Multi-page receipts have to be supplied as a single document.

3. Online APIs via the DATEV developer portal

For automatic exchange without handing over files, DATEV offers online APIs, for example for receipts and for posting data made available through the DATEV data center. DATEV calls this “Cloud Integration”. The process according to the DATEV developer portal:

• Registration of the software vendor in the developer portal, creation of an organization with an advisor number and of an application
• Booking the mandatory, paid onboarding package from DATEV
• Implementation against the interface specifications in the test environment (sandbox); for the Buchungsdatenservice (DATEV posting data service), an additional check of the file format with sample files
• Technical review by DATEV. After that, you get production access, initially limited to three months, until acceptance in live operation

According to DATEV, providers without a partnership can also implement interfaces. DATEV lists them in a separate list of interface providers, apart from the marketplace partners. Individual requirements and versions change. The current state in the developer portal is what counts.

Which route fits you?

What do companies and tax advisors have to approve?

With DATEV, it almost never works without the tax advisor. These points should be settled before the project:

• Advisor and client number: Both appear in the header of every EXTF file and identify the client in the online APIs. You get them from your tax firm.
• Chart of accounts and account length: Which chart of accounts applies, and how many digits do the general ledger accounts have? Both must be correct in the file.
• Start of the fiscal year: It is stated in the header record. In the DATEV format, the document date contains only day and month, and DATEV derives the year from the fiscal year. A wrong start leads to wrong periods.
• Data services: For online transfers, the tax firm must order or activate the matching data service for your client, for example for posting data or receipts.
• Permissions: The person who authorizes the integration needs the right permissions in DATEV for the client.
• Account assignment: Which revenue accounts, BU-Schlüssel (DATEV tax keys) and offsetting accounts apply to which cases? It is best to define these rules together with the tax firm.

Typical errors

• Wrong header record

  The identifier, version or format category is wrong, or advisor and client numbers do not match the records. The import then aborts.

• Wrong account length

  The file uses four-digit accounts, the client uses five-digit ones. According to DATEV, the account length must match the client, otherwise the import fails or the accounts do not fit.

• Number formats

  The DATEV format uses a comma as the decimal separator and a semicolon as the field separator. An export with a period or another separator reads wrong amounts or fails. The default character set is ISO-8859-1. UTF-8 works only with a byte order mark (BOM) and not on every import route.

• Duplicate handover

  The same file is imported twice, or an integration resends after an error. Without protection against duplicates, you get double postings.

• BU-Schlüssel

  If the BU-Schlüssel (tax key) does not match the account functions, for example on an automatic account, DATEV reports an error. If a key is missing, for example for deliveries abroad, the VAT is wrong. This often only shows up in the advance return.

• Locked by accident

  The flag in the header record is set to Festschreibung (posting lock) by default. If the tax firm wants to review the batch first, the integration must explicitly switch this off. Locked postings can only be corrected through a Generalumkehr (DATEV reversal posting).

Checklist before you start

• Does your tax firm do the bookkeeping, or do you book in DATEV yourself?
• How often should data flow: daily, weekly or at month-end close?
• Should only postings be transferred, or receipts as well?
• Are advisor and client number, chart of accounts, account length and fiscal year available?
• Has the tax firm ordered or activated the required data services for the client?
• Is there an agreed list of accounts and tax keys for your cases?
• Who checks the first transfers before the integration goes live?

How we connect DATEV

We build direct integrations from your shop, your ERP or your CRM to DATEV. Which route fits, we clarify with you and your tax firm in the free 30-minute integration check. Often the EXTF file is the fastest and most robust start. Details under DATEV integration and for individual systems under Shopware to DATEV, Shopify to DATEV and JTL-Wawi to DATEV.

Updated: 10/21/2026