White Opinion No. Custodians of the municipal and county treasuries are required to keep separate records of the amount of these funds on deposit.
Interest held in trust by a county for another party is an increment that accrues to the owner.
Thus, the state of Texas is the owner of the special funds collected and is entitled to the accrued interest thereon. In answer to your second question, both statutes provide that municipal or county treasuries may retain ten percent of the funds collected as service fees. As owner of the ten percent service fee, the county is entitled to interest on that ten percent of the fund. The county is entitled to retain interest earned on its service fee.