# Release History
source: https://developer.mastercard.com/user-account-management-service/documentation/release-history/index.md

This section contains a history of what has been implemented in the User Account Management API.

Following are the list of changes (in reverse chronological order).

| **Release Dates** | **Release Version** |                                                                                                                                                                                                                                                                                                                     **Description**                                                                                                                                                                                                                                                                                                                      |
|-------------------|---------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| September 2023    | v5.0                | * Introduced the ability to filter the accounts based on the programIdentifier [Lookup Identifiers](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/lookup-identifiers/index.md) endpoint. * Introduced the ability to verify user based on answers to the security questions [Verify User](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/user-management/index.md#verify-user) endpoint.                                                                                                                                                                            |
| August 2023       | v4.1                | * Added User-Defined Fields (UDFs) 2, 3, and 4 for the [POST /users](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/user-management/index.md#enroll-user) endpoint. * Updated [Lookup Identifiers](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/lookup-identifiers/index.md) capability to return array of sensitive identifiers like BAN and BCN in the response. * Added PCLOUser object response for [Retrieve User](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/user-management/index.md#retrieve-user) endpoint. |
| July 2023         | v4.0                | * Expanded [Lookup Identifiers](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/lookup-identifiers/index.md) capability to return sensitive identifiers like BAN and BCN in the response. Certain services require different token identifiers to complete a function (such as requesting a lost or stolen card). This section documents how to exchange sensitive identifiers with their token counterparts, and vice versa. * Introduced offset based pagination. * API performance improvements.                                                                                                             |
| May 2023          | v3.1                | * Updated Primary flags in [Account Groups](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/account-management/index.md#group-accounts). This change allows an account to be moved to another household and updates the primary flag for both households, enforcing only one primary account in the household. * Minor bug fix for User-Defined Fields (UDFs) for [PUT /accounts](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/account-management/index.md#update-account) endpoint.                                                                                |
| April 2023        | v3.0                | Introduced the ability to group accounts into households through the [Account Groups](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/account-management/index.md#group-accounts) endpoint.                                                                                                                                                                                                                                                                                                                                                                                                                     |
| March 2023        | v2.0                | Introduced customer validation and validation questions through the [Retrieve User](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/user-management/index.md#retrieve-user) endpoint.                                                                                                                                                                                                                                                                                                                                                                                                                           |
| February 2023     | v1.0                | Initial publication of the User Account Management to Mastercard Developers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|                   |                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |

Refer to the [Use cases](https://developer.mastercard.com/user-account-management-service/documentation/use-cases/index.md) section for a functional explanation and the [API Reference](https://developer.mastercard.com/user-account-management-service/documentation/api-reference/index.md) section for technical details.