H.B. No. 4591 amends existing laws regarding contributions to and benefits under certain fire and police pension funds in Texas. The bill introduces the term "Qualified actuary," defining it as an actuary meeting specific qualifications outlined in Section 10A(b)(1). It also modifies the provisions related to wage deductions for fund contributions, allowing for adjustments based on decisions made by the board of trustees, and clarifies the conditions under which changes to the pension fund can be made, including the requirement for approval by a qualified actuary and a majority vote from contributing members.

Additionally, the bill establishes new sections regarding city or town contributions to the pension fund, mandating a minimum contribution of 18% of total member wages, with provisions for increases or decreases based on actuarial assessments. It allows for joint increases in contributions from both the city or town and the members if deemed necessary by a qualified actuary. The changes aim to ensure the financial stability of the pension funds while protecting the rights of current and future members. The act is set to take effect on September 1, 2025.