User and Account Management

Overview

This guide describes how to manage users linked to one or more accounts on Fits. It covers creating a user with linked accounts, checking those links, recommended limits, and White Label behavior.

1. Creating a User with Multiple Linked Accounts (CreateUser)

CreateUser allows linking multiple accounts to a single user at creation time, using the AccountsTaxNumber[] field.

1.1 How linking works

• Accounts are linked at the moment the user is created — there is no separate endpoint to link accounts after the user already exists.
• The AccountsTaxNumber[] array does not follow any priority order: there is no concept of a "primary account" among the accounts provided.
• The accounts provided can belong to different Tax Numbers (Tax IDs) — they do not need to belong to the same account holder.

{
  "Method": "CreateUser",
  "PartnerId": "",
  "BusinessUnitId": "",
  "UserName": "",
  "Mail": "",
  "AccountsTaxNumber": [
    "TAX_NUMBER_1",
    "TAX_NUMBER_2"
  ]
}

1.2 Adding and removing accounts after creation

• It is not possible to add new accounts to an already-created user via API — linking only happens at creation time.
• Removing accounts linked to an existing user is done through the Admin Portal, with support from the support team — there is no API method for this action.

1.3 Invalid accounts in the array

The accounts provided in AccountsTaxNumber[] are processed individually and sequentially — each Tax ID in the array is processed one after another, in the order it was sent.

• If an error is identified while processing one of the Tax IDs, that item is not completed and processing is stopped — the remaining items in the array, not yet processed, are also not executed.
• Tax IDs that were already processed successfully before the failure remain completed and are not undone or affected by the later error.

Example: for a request containing 5 Tax IDs, if an error occurs on the 3rd item, the first two remain successfully processed, the 3rd is rolled back, and the 4th and 5th are never processed.

Important: since processing is sequential and stops at the first error, the order of the Tax IDs in the array determines which accounts end up linked in case of a failure partway through the list. It is recommended to advise the client to check the call's response to confirm which accounts were actually linked before handling the error.

A user with no linked accounts at all is considered a valid state in the system.

2. Recommended Account Limit per User

• As a practical reference, starting at approximately 50 accounts linked to the same user

This number (~50 accounts) is a practical reference. For journeys with volume well above thiscase-by-case evaluation with the technical team is recommended before scaling the implementation.

3. Account Selection and Switching in White Label

White Label supports account selection and switching for users with multiple linked accounts. This switching is handled by the front end — that is, it is a behavior already available in the interface, and not something the client needs to implement via API.

• Switching accounts does not affect the authentication token or session — no new authentication is required when switching accounts.
• There is no difference in behavior between White Label and the native Fits environment: account switching works the same way in both.