How to Connect DATEV to MCP for AI-Powered Accounting

DATEV with AI Agents via MCP

DATEV is the accounting and tax software that most German tax consultants (Steuerberater) and many of their clients work in. AnythingMCP turns DATEV's official Online APIs into an MCP server, so Claude, ChatGPT and other MCP clients can read DATEV data through tools instead of screenshots and exports.

What the DATEV connector covers today: six read-only tools on two DATEV API products, accounting:clients (Mandanten master data) and accounting:documents (DATEV Unternehmen online, DUO). It does not write to DATEV, and payroll, bookings and DMS are not part of it.

What you can ask

These prompts work in any MCP client connected to the DATEV server; the tool each one uses is in brackets.

• "How many Mandanten can I see in DATEV, and what are their client numbers?" (datev_list_clients)
• "Get the address on file for Mandant 10023." (datev_list_clients, then datev_get_client)
• "Which Mandanten have DATEV Unternehmen online document access?" (datev_documents_list_clients)
• "List the Belegtypen for Bäckerei Schmidt, so I know which document type to use for incoming invoices." (datev_list_document_types)
• "Can Bäckerei Schmidt upload TIFF files to DUO?" (datev_get_duo_version)
• "Show me the DUO view of Bäckerei Schmidt next to its master record." (datev_get_documents_client and datev_get_client)

What you need

1. A registered app on the DATEV developer portal: confidential client, OpenID Connect Authorization Code Flow, redirect URI <your AnythingMCP URL>/api/mcp-oauth/callback (on AnythingMCP Cloud: https://cloud.anythingmcp.com/api/mcp-oauth/callback).
2. The app subscribed to accounting:clients 2.0 and accounting:documents 2.0.
3. Its client ID and secret for DATEV_CLIENT_ID and DATEV_CLIENT_SECRET (the secret is shown once).
4. A DATEV-Konto user with SmartLogin or SmartCard/mIDentity. DATEV does not offer client_credentials for these APIs: every call is made on behalf of a person, with that person's rights.
5. For production data, DATEV's production approval of your app. Until then there is a separate DATEV Online APIs (Sandbox) connector, already pointed at the sandbox endpoints.

Quick Setup

On AnythingMCP Cloud: open Connectors, install DATEV Online APIs (or the Sandbox connector), paste the client ID and secret, then click Authorize with Provider on the connector page and log in with your DATEV-Konto.

Self-hosted:

curl -fsSL https://raw.githubusercontent.com/HelpCode-ai/anythingmcp/main/docker-compose.quickstart.yml -o docker-compose.yml
printf 'JWT_SECRET=%s\nENCRYPTION_KEY=%s\n' "$(openssl rand -hex 32)" "$(openssl rand -hex 32)" > .env
docker compose up -d

Open http://localhost:3000/connectors/store, import the DATEV adapter, enter the OAuth 2.0 credentials and run the same one-time authorization.

After that, AnythingMCP keeps the tokens fresh (DATEV confidential clients get two-year rolling refresh tokens) and adds the mandatory X-DATEV-Client-Id header to every call. Point your MCP client at your AnythingMCP MCP URL; for Claude, the steps are in Connect DATEV to Claude.

Available Tools

The clientId parameter on the per-client tools is the Mandant's UUID from datev_list_clients, not your OAuth client ID.

Scopes and environments

The connector requests datev:accounting:clients accounting:clients:read accounting:documents in one consent screen. Production uses login.datev.de/openid/authorize and api.datev.de/token; the Sandbox connector uses login.datev.de/openidsandbox/authorize and sandbox-api.datev.de/token. Credentials are the same for both; only the approval differs.

Troubleshooting

• Token exchange fails after a successful DATEV login. Usually the client secret: copied incompletely, or from another app. Generate a new one, save it in the connector and authorize again. The connector already sends it via HTTP Basic, as DATEV requires.
• Document tools fail, client tools work. The app lacks the accounting:documents 2.0 subscription, or the Mandant has no DUO access.
• Everything works in the sandbox, nothing in production. The app is not approved for production yet. Keep testing on the Sandbox connector.
• The client list is shorter than expected. The tools return what your DATEV user may see. More Mandanten need more rights in DATEV, not a connector change.

FAQ

Which DATEV data can AI agents read through this MCP server? Mandanten master data from accounting:clients, and from accounting:documents the list of DUO-enabled Mandanten, their document types and DUO version details. Payroll, bookings, DMS and document uploads are not included.

Does it work in Claude Desktop and Claude Code? Yes. A custom connector you add on claude.ai is also available in Claude Desktop, and Claude Code adds the same URL with claude mcp add --transport http. Other clients that support remote MCP servers connect to the same URL.

Is it free? AnythingMCP is open source under AGPL-3.0, so self-hosting is free, including commercial use inside your own company. AnythingMCP Cloud comes with a 7-day free trial. Access to DATEV itself is governed by your DATEV contract and the developer portal's terms.

Is my data stored by AnythingMCP? Your DATEV credentials and tokens are stored encrypted (AES-256-GCM) and are never passed to the AI client. Tool results go to the AI client you connected, and every call is recorded in your workspace's audit log. AnythingMCP Cloud is hosted in Frankfurt, Germany; self-host if the data must stay on your own infrastructure.