Tex. Gov't Code § 814.012

If, as of the fourth anniversary of the death of a member or annuitant, the retirement system has not paid benefits and a claim for benefits is not pending with the retirement system based on the death of the member or annuitant, the accumulated contributions of the deceased member or the balance of the reserve for the deceased annuitant reverts to the benefit of the retirement system. The retirement system shall transfer funds reverted under this section to the state accumulation account.