> ## Documentation Index
> Fetch the complete documentation index at: https://docs.maesn.com/llms.txt
> Use this file to discover all available pages before exploring further.

# DATEV Unternehmen Online

> Integrate DATEV Unternehmen Online easily with Maesn’s Unified API. See the documentation with detailed system coverage and setup prerequisites.

**TARGET\_SYSTEM:** `datev-uo` `datev-uo-longtoken`

<div className="integration-table">
  |                      |                          Read                          |                         Create                         |                         Update                         |                         Delete                         |                         Webhook                        |
  | -------------------- | :----------------------------------------------------: | :----------------------------------------------------: | :----------------------------------------------------: | :----------------------------------------------------: | :----------------------------------------------------: |
  | Accounts             | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="phone" iconType="light" color="#828282" /> |
  | Async task           | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="phone" iconType="light" color="#828282" /> |
  | Bank accounts        | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Bills                | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Bill lines           | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Booking proposals    | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Contacts             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Customers            | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Credit notes         | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Dimensions           | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Expenses             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Files                | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Fiscal years         | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Goods receipts       | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Goods receipt lines  | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Invoices             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Invoice lines        | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Items                | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Journals             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Journal entries      | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Offers               | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Offer lines          | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Open items           | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Payments             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Payment terms        | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Projects             | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Purchase orders      | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Purchase order lines | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Sales orders         | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Sales order lines    | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Suppliers            | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Tax rates            | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Transactions         | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Trial balance        | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Units                | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Users                | <Icon icon="check" iconType="solid" color="#4db975" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
  | Vendor credits       | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> | <Icon icon="xmark" iconType="solid" color="#828282" /> |
</div>

<Icon icon="check" iconType="solid" color="#4db975" /> = Supported by Maesn <br />
<Icon icon="phone" iconType="light" color="#828282" /> = On demand - contact us<br />
<Icon icon="xmark" iconType="solid" color="#828282" /> = Not supported by DATEV Unternehmen Online <br />

## What is DATEV Unternehmen Online

DATEV Unternehmen Online is one of DATEV's online applications. It allows tax advisors and companies to exchange receipts and accounting data via the Internet. It can also be used to transfer data from customers' ERP- or accounting system to other DATEV applications, such as DATEV Rechnungswesen, which is an application for accounting used by small- and medium sized companies.

<img src="https://mintcdn.com/maesn/gCd41Ws3USFubam4/images/datev_overview.svg?fit=max&auto=format&n=gCd41Ws3USFubam4&q=85&s=4ec2e0190d534d20c01ab67e383a8197" title="DATEV infrastructure" alt="Diagram showing overview of DATEV application infrastructure" width="1040" height="480" data-path="images/datev_overview.svg" />

## How to connect to DATEV Unternehmen Online

To allow your customers to link your application with their DATEV Unternehmen Online accounts, it is required to set up a DATEV Unternehmen Online App.

<Steps>
  <Step title="Configure your integration in the maesn API">
    Since maesn has partnered with DATEV to help bring software companies to successful integrations quickly, the entire setup process is executed with maesn. There is no need to book consulting packages with DATEV.

    Everything from setting up client credentials and getting sandbox access, to getting your integration approved by DATEV is done by maesn.

    * Get in touch with your contact person at maesn to configure the API and DATEV OAuth client.

    If you are not sure who your technical contact is, do not hesitate to [reach out to us](https://www.maesn.com/contact).
  </Step>

  <Step title="Testing your integration in a production environment">
    To test your integration against a live production environment is both recommended and necessary, before offering the functionality to your customers.

    You will need an instance of DATEV Unternehmen Online with the subscriptions to the relevant services for your use case to run your integration in production.

    * Talk to us for advice on how to achieve this in a fast and cost-effective way!
  </Step>
</Steps>

## Authenticate with the long access token

Provide your customer the long access token procedure to authenticate to DATEV Unternehmen Online. The token is valid for 2 years and can be used for authentication throughout that period to the API.
There are two ways to retrieve a long access token:

* Use our [**Interactive Authentication Flow**](/authentication#interactive-authentication-flow)
* Or manually execute each step for more control over the UI

### 🔁 Option 1: Interactive Authentication Flow

<Steps>
  <Step title="Authenticate to DATEV Unternehmen Online">
    * Log in to `datev-uo-longtoken` using the `/auth` endpoint.  Make sure to include the query parameter `environmentSelection=true` in the request.
  </Step>

  <Step title="Choose your Company">
    * From the list, select the target company for your API usage.
    * The selected company's ID is stored automatically — you do not need to send it in subsequent requests.
  </Step>

  <Step title="Retrieve the long token">
    * Click **"submit"**.
    * Accept the connection to your application to complete the process and retrieve your token.
  </Step>
</Steps>

### ⚙️ Option 2: Manual Token Retrieval

<Steps>
  <Step title="Authenticate to DATEV Unternehmen Online using the short token">
    * Log in to `datev-uo` using the `/auth` endpoint.

    * Retrieve the Account key from the authentication response.
  </Step>

  <Step title="GET company ID">
    * Fetch the company list using the `Get Companies` endpoint.

    * From the list, select the target company to use for the API calls.
  </Step>

  <Step title="Authenticate to DATEV Unternehmen Online using the long token">
    * Authenticate again using the `/auth` endpoint, but this time with `datev-uo-longtoken` target system, providing the chosen companyId as input.

    * Complete the authentication process.
  </Step>
</Steps>

**Warning:** The long token is only valid for API calls that include the specified company in the input.