TaxGraph (Preview)

Research German tax law with cited primary sources. TaxGraph answers tax law questions from a curated database of German statutes, federal and fiscal court decisions, BMF letters, guidelines, and decrees, and returns structured legal-opinion style answers through its Model Context Protocol (MCP) server.

This connector is available in the following products and regions:

Service Class Regions
Copilot Studio Premium All Power Automate regions except the following:
     -   US Government (GCC)
     -   US Government (GCC High)
     -   China Cloud operated by 21Vianet
     -   US Department of Defense (DoD)
Logic Apps Standard All Logic Apps regions except the following:
     -   Azure Government regions
     -   Azure China regions
     -   US Department of Defense (DoD)
Power Apps Premium All Power Apps regions except the following:
     -   US Government (GCC)
     -   US Government (GCC High)
     -   China Cloud operated by 21Vianet
     -   US Department of Defense (DoD)
Power Automate Premium All Power Automate regions except the following:
     -   US Government (GCC)
     -   US Government (GCC High)
     -   China Cloud operated by 21Vianet
     -   US Department of Defense (DoD)
Contact
Name TaxGraph Support
URL https://www.tax-graph.com/faq
Email support@tax-graph.com
Connector Metadata
Publisher TaxGraph GmbH
Website https://www.tax-graph.com
Privacy policy https://www.tax-graph.com/datenschutz
Categories AI;Finance

TaxGraph

TaxGraph is a research service for German tax law. The TaxGraph MCP server lets agents in Microsoft Copilot Studio and Microsoft 365 Copilot research German tax law questions against a curated database of statutes, federal fiscal court decisions (BFH), fiscal court decisions (FG), BMF letters, administrative guidelines, and decrees. Results are structured, legal-opinion style answers in which every legal statement is backed by a linked primary source. Historical versions of statutes are resolved correctly per assessment period.

TaxGraph is built for tax advisors, in-house tax departments, and auditors who need reliable research results with verifiable citations.

Publisher: TaxGraph GmbH Website: https://www.tax-graph.com

Prerequisites

  • A TaxGraph account with an active subscription. Sign up at https://www.tax-graph.com/signup.
  • Users authenticate with their TaxGraph account via OAuth 2.0 when creating a connection.

Supported operations

The server exposes a single tool:

Tool Description
tax_law_research_agent Runs a German tax law research request end to end. Supports starting a new research, polling a running research session, and answering follow-up questions from the research agent.

Call modes

Parameters Behavior
message only Starts a new research session and returns a session_id.
session_id only Fetches the state or result of a running session.
session_id and message Answers a follow-up question, only while the session status is awaiting_user.

Return states

Status Meaning
done The research is finished; the structured answer is in result, cited sources in citations.
running The research is still in progress; call again with the session_id.
awaiting_user The research agent asks a follow-up question (in interrupt); present it to the user and return the answer as message.
error Invalid parameter combination; see the error field.

Obtaining credentials

Users sign in with their TaxGraph account through the OAuth 2.0 flow when creating a connection. No API key is required. Access to the research tool requires an active TaxGraph subscription; without one, the server returns an entitlement error with instructions.

  1. Add the TaxGraph connector to your agent and choose Create connection.
  2. You are redirected to the TaxGraph sign-in page (https://mcp.tax-graph.com/mcp/authorize).
  3. Sign in with your TaxGraph account and grant access.
  4. You are redirected back and the connection is ready.

Technical OAuth 2.0 details of the TaxGraph MCP server:

  • Authorization URL: https://mcp.tax-graph.com/mcp/authorize
  • Token URL: https://mcp.tax-graph.com/mcp/token
  • Refresh URL: https://mcp.tax-graph.com/mcp/token
  • Scopes: openid, profile, email
  • PKCE: S256 (required)
  • Token endpoint authentication: client_secret_post
  • Redirect URI to allow-list: https://global.consent.azure-apim.net/redirect/<connector name> (assigned by Microsoft)

A dedicated OAuth client (client ID and client secret) is registered by TaxGraph GmbH for the Microsoft Power Platform connector and supplied through Partner Center. The clientId value in apiProperties.json is a placeholder and must not contain a real client ID in source control.

For setup instructions see https://www.tax-graph.com/product/microsoft-copilot. For support contact support@tax-graph.com.

Known issues and limitations

  • The service covers German tax law only, and answers are in German.
  • A research run typically takes several minutes. The tool is asynchronous: start the research, then poll with the session_id until the status is done.
  • Documents are cited with links to the TaxGraph document viewer (https://www.tax-graph.com); opening cited sources requires a TaxGraph account.
  • The corpus covers German statutes, BFH and FG decisions, BMF letters, guidelines, decrees, and double taxation agreements. Commercial commentary literature and proprietary sources (e.g., the OECD model commentary) are not included.

Actions

TaxGraph MCP server

Streamable HTTP endpoint of the TaxGraph MCP server for German tax law research.

TaxGraph MCP server

Operation ID:
InvokeServer

Streamable HTTP endpoint of the TaxGraph MCP server for German tax law research.