DATEV API Integration
DATEV is a family of systems and web services, from DATEV Unternehmen Online to DATEV Rechnungswesen, each with its own data format and its own approval path. Maesn is an official DATEV Interface Partner and covers all of them through one REST API, so an approved DATEV integration takes days rather than the months the process usually costs.
All DATEV complexity covered within Maesn
A direct DATEV integration is gated three times before the first call succeeds, and each gate is held by someone other than you. Through Maesn all three are already open.
A REST API for DATEV
Every service underneath speaks its own format. Maesn converts them, so you send and read JSON on the same endpoints you use for every other system.
Start tomorrow and become an official DATEV Interface Partner with us
Client credentials, sandbox access and the approval of your integration by DATEV are set up through Maesn. Focus on developing one integration to Maesn, we cover the rest.
Free sandboxes for DATEV
A ready-to-use test environment for Unternehmen Online and for Rechnungswesen, so building starts on day one rather than after a DATEV process finishes.
What is left for your team is the part worth owning: deciding which data moves and when.
Bring your use case and we will tell you which DATEV services it needs.
The two ways to work with DATEV
Small companies usually hand the bookkeeping to their tax advisors, bigger companies do it on their own. How they do it decides which product they have in use.
Bookkeeping done by the tax advisor
Most small and mid-sized companies
The company works in Unternehmen Online, and an integration still reaches Rechnungswesen
- 1
The record is created in your product
An invoice, a bill or an expense appears where the business already works.
- 2
DATEV Unternehmen Online takes it
The platform both sides share. It is the exchange point between the business and its tax advisor, not the place where anything is booked.
- 3
The tax advisor books it in Rechnungswesen
The advisor reviews and amends the records and posts them. The company never opens Rechnungswesen itself, which does not stop an integration from writing into the advisor's instance directly, identified through the advisor and client identification.
Bookkeeping done by the company
Self-bookers, usually with an in-house finance team
The company works in Rechnungswesen itself, with Unternehmen Online in front of it
- 1
The record is created in your product
The same starting point. Nothing about your integration changes with the setup.
- 2
DATEV Rechnungswesen books it
The finance team posts the entries in house. Journal entries and contacts can be written straight into it.
- 3
Unternehmen Online sits in front of it
Self-bookers run it as well, as the cloud platform through which they reach their own Rechnungswesen instance, rather than as the route to an advisor.
Either way, it is the same integration. You write to DATEV through one API, and whether a tax advisor or the company posts the entry is a setting on their side rather than a branch in your code.
DATEV Rechnungswesen is the full suite. It comes as a variant a company runs itself and as a variant the tax advisor runs, and in both cases it is the same product: the one built to represent every single tax and financial process in the form German legislation expects. DATEV Unternehmen Online is something else. It is primarily the cloud-based platform for exchanging data with Rechnungswesen.
That is why a company which does not do its own bookkeeping runs Unternehmen Online and nothing else, exchanging data with the advisor who works in Rechnungswesen, and why a company that does its own bookkeeping still has Unternehmen Online, as the cloud route to its own Rechnungswesen instance. Neither case stops you from integrating with Rechnungswesen directly. Even where only Unternehmen Online is in use, an integration can reach the Rechnungswesen instance running at the customer’s tax advisor, identified through the advisor and client identification.
The split shows up in what each one accepts. Booking proposals, Expenses, Transactions belong to Unternehmen Online, Contacts, Journal entries to Rechnungswesen, and Files is the one object both of them take.
Four DATEV data services, one interface
Each DATEV service carries its own payload and points at one of the two systems. Maesn sits above all of them, so your application talks to one API instead of four.
Unified APIOne interface across the entire DATEV landscape, we translate between your application and every DATEV data service.
Belegbilderservice
Upload invoices, bills and credit notes as document images.
Rechnungsdatenservice 1.0
Post structured invoice, bill and credit note data as booking proposals.
Datenservice Kassenarchiv
Cash register data. Planned, not available today.
Buchungsdatenservice
Post reconciled journal entries into the accounting system.
Datenservice Export Rechnungswesen
Pull journal entries, the chart of accounts, payment terms, fiscal years and a trial balance out of DATEV.
All services are subsumed under our Unified API.
The Belegbilderservice posts document images (PDF, JPG) to DATEV Unternehmen Online and enables the provision to DATEV Rechnungswesen. It is usually combined with the Buchungsdatenservice, which posts the journal entries those documents belong to and carries no image itself.
The Rechnungsdatenservice 1.0 takes the document together with its structured data in one call, so the advisor gets a booking proposal instead of a scan to type up. That is why it does not need the Belegbilderservice alongside it. The Buchungsdatenservice writes reconciled journal entries straight into Rechnungswesen, and it is the one path that skips the review step. The Datenservice Export Rechnungswesen is the only one that reads.
A fifth, the Datenservice Kassenarchiv for cash register data, is planned and not available today, with no date attached. DATEV also runs an e-invoicing platform with no target system of its own here yet, covered in our guide to the DATEV E-Rechnungsplattform, and which of the two systems behind the services a use case belongs to is answered in the comparison of Unternehmen Online and Rechnungswesen.
Pull data out of Rechnungswesen
DATEV data extraction is complex. We have engineered the deep integrations to make it work.
- Journal entries
- Pull all journal entries with related data out of DATEV.
- Chart of accounts
- Pull the account structure every booking is posted against.
- Trial balances
- Pull the trial balances out of DATEV.
We have implemented the DATEV Datenservice Export Rechnungswesen in our Unified API, so you can pull data easily via REST. Now you can ask the two questions that matter: what was booked, and what is still outstanding. You get the answer from the authoritative source, not a copy. It arrives normalised through our common data model, so it looks the same shape as every other system. Large result sets page and filter using the same rules you use elsewhere. Our export service guide walks through a full retrieval.
Fifteen minutes is enough to see a real trial balance come out of a DATEV instance.
Rally launched its DATEV integration in days
Rally is a financial platform for businesses that operate vehicle fleets, and DATEV was on the critical path to their German launch.
“Maesn transformed the way how to integrate with DATEV. What would have been a complex long process turned into a smooth, intuitive process thanks to their REST API, DATEV sandbox and certification process.”
Three reasons to reach the DATEV API through Maesn
Three reasons teams route their DATEV integration through Maesn rather than building it directly.
Go live today
The multi-stage approval process for DATEV interfaces is the #1 reason integrations slip. Maesn is an official DATEV Interface Partner, so we shepherd your integration through the process under your own name.
REST API only, simple authentication
CSV/XML files, DATEV formats and asynchronous endpoints create friction. We have unified it all into our common data model, so you work with one REST interface.
Deep DATEV expertise
We know how DATEV actually works. Without proper guidance, setups get complicated fast, especially involving the company's tax advisor. We support you and your customers every step of the way.
Get listed in the DATEV Marketplace under your own name
A DATEV Marketplace listing puts your software where tax advisors look for it, under your own name and your own logo. An integration built through Maesn counts exactly the same as a direct one for the qualification.
More than 25 active connections
The listing follows traction, so it comes after your first customers are live. Connections running through Maesn count the same as direct ones.
Customer interviews
DATEV talks to the businesses using your integration. That is a conversation you can only have once real users depend on it.
A strategic fit with DATEV
An evaluation by the DATEV partner team on what your software adds for their customers. Maesn guides you through the qualification rather than handing you a form.
None of the three can be bought forward. They all describe a product that is already in use, which makes the listing a milestone rather than a launch task.
DATEV SmartCard and SmartLogin
DATEV offers more than one way for a user to authenticate. All of them are supported by Maesn and embedded in unified authentication, including multi-company support.
- SmartCard
- Hardware-based DATEV login
- SmartLogin
- DATEV's app-based login
One account key, whichever method your customer uses
- datev-uo
- DATEV Unternehmen Online.
- datev-rewe
- DATEV Rechnungswesen.
Maesn embeds the full DATEV login, so there is no second implementation to maintain when DATEV changes something on their side.
- 1
Send the user to the flow
Call /auth for the target system with environmentSelection=true. The DATEV login opens, with SmartCard or SmartLogin as the customer prefers.
- 2
The company is chosen
The customer picks the DATEV company to connect. The ID is stored for you, so it does not have to travel on every later request.
- 3
You receive the account key
One key, the same shape as every other system on the platform. No DATEV-specific branch in your code.
Whichever method your customer uses, the result is one account key and no DATEV-specific branch in your code, because the whole login is embedded behind the unified authentication flow.
What the tax advisor activates in DATEV
One part of a DATEV integration is never ours and never yours. Knowing it early saves the week that otherwise goes to guessing.
- The tax advisor books the services
- DATEV web services are ordered and activated by the customer's tax advisor inside their own DATEV instance, and they stay responsible for them. There is no API that switches them on from outside.
- Authentication permission
- The person holding the access medium needs at least standard access rights for the app. Rights are configured through DATEV Rechteverwaltung Online, a separate tool with a great many settings.
- Where we come in
- For every use case we name the exact services and rights that have to be in place, and we join the call with your customer when a setup still does not behave.
We walk through the services and rights with you, and with your customer when it helps.
DATEV API questions
What is the difference between DATEV Unternehmen Online and DATEV Rechnungswesen?
Can I read data out of DATEV, or only write into it?
Do I become a DATEV Schnittstellenanbieter myself?
How do I get a DATEV sandbox for development?
Which DATEV authentication methods are supported?
Who activates the DATEV services for a customer?
Which DATEV interfaces are there, and which of them does Maesn cover?
How does a DATEV interface work in practice?
See both DATEV systems in detail
Which of the two you build against follows from who does the bookkeeping, and both run through the same Maesn API.
Interface PartnerDATEV Unternehmen OnlineDATEV
DATEV's document exchange portal connecting businesses directly with their tax advisor's environment.
Interface PartnerDATEV RechnungswesenDATEV
Standard accounting platform for German tax advisors and larger self-booking companies across Germany.