Thomson Reuters API facilitates client integration with the GoSystem product. Using services, client applications can check e-file status, import or export tax return data, print returns, and more. 
This document describes the available APIs, their functionality and programming interfaces, and the authentication requirements for each service.

Auth code grant type:

1. The client app can use oauth2/v1/auth-code endpoint to generate one time use Auth code for step no 3.
2. OR In the browser go to https://api.thomsonreuters.com/gosystem/oauth2/v1/authorize .Query Parameters client_id, and response_type are required to be added to this URL: 
   Query Parameters:
   client_id: Unique id for the client. To be generated as part of API onboarding.
   response_type: code (it should be defaulted to "code")
   state: A random unique identifier per request. This will be sent back to the client app on the callback URL and must be validated.
   1. Once the user logs in using SSO, an Auth code will be generated and the user will be redirected to a configurable (callback) URL on the client app.
   2. The callback URL should be configured in the API gateway during the onboarding process.
3. The client app needs to use this Auth code to make a call to /oauth2/v1/token endpoint which will then return a bearer access token.
4. The client app can use oauth2/v1/refresh endpoint to refresh the access token when expired

Note: The scope required to access GoSystem APIs is 'urn:tr:gosystem:auth:api:taxreturn'.

Client Credentials grant type:

This type has no dependency on the API Key. This works off of a machine user. Make sure to request for Service Account based Company and Company App set up when requesting TR for your client id and secret.

Here cURL command to generate the token using Key and Secret:

curl --location 'https://api.thomsonreuters.com/gosystem/oauth2/v1/token' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'grant_type=client_credentials' \
--data-urlencode 'client_id=<<Your Client Id Here>>' \
--data-urlencode 'scopes="urn:tr:gosystem:auth:api:taxreturn"' \
--data-urlencode 'client_secret=<<Your Client Secret>>' \