H.B. No. 3521 amends the police officers' public retirement system for certain municipalities in Texas, introducing a new definition of "catastrophic injury" that includes severe, duty-related injuries from external events like motor vehicle collisions or gunshot wounds, while excluding certain diseases and injuries such as infectious diseases and anxiety disorders. The bill also modifies the definitions of "employee" and "salary" to include individuals in classified or appointed positions within the police department. Additionally, it revises the governance structure of the pension system's board, including the election process and stipulations for board member service, and allows for stipends and reimbursement for board members who are not city employees.

Further changes include the stipulation that once a member separates from service, their monthly service pension payments will resume without adjustments for subsequent years of service or pay, and members are ineligible for refunds of contributions made during any subsequent service. The bill introduces new provisions for disability pensions, including deadlines for filing applications and the board's authority to accept late applications under certain conditions. Members receiving disability pensions will need to submit annual income documentation, which may affect their pension payments, and the bill clarifies conditions for reclassifying disability pensions. These changes will take effect on July 1, 2025, contingent upon a two-thirds vote from both houses of the legislature, or on September 1, 2025, if that vote is not achieved.