H.B. No. 4873 proposes significant amendments to the retirement systems for firefighters in certain Texas municipalities, specifically adjusting the population range for cities eligible for the Firefighters Relief and Retirement Fund from "450,000 to 500,000" to "950,000 to 1,050,000." The bill introduces new definitions related to the fund, enhances the board of trustees' composition by increasing firefighter and retiree representatives, and adds a public member with specific qualifications. It also establishes a four-year term for board members, modifies meeting frequencies, and mandates experience studies every five years to ensure the fund's governance and operational transparency.

Additionally, the bill addresses retirement benefits, including provisions for military service credit, a Deferred Retirement Option Plan (DROP), and annual cost-of-living adjustments for certain members and survivors. It specifies contribution rates for firefighters and municipalities, mandates risk-sharing valuation studies, and clarifies the election process for board members. The bill aims to enhance the financial security and benefits structure for firefighters while ensuring compliance with federal regulations and improving the overall governance of the retirement fund.