(a) Except as provided by Subsection (d), if a member dies before retirement, the amount in the member's individual account in the employees saving account at the time of death is payable as a lump-sum death benefit.
(b) Except as provided by Subsection (c), the benefit provided by this section is payable to a person designated by the member in a signed and witnessed document filed with the retirement system before the member's death. A designation, change, or revocation of a beneficiary in a will or other document not filed with the retirement system is not effective. If a member does not designate a beneficiary or if the beneficiary designation cannot be made effective, the benefit is payable to the member's estate.
(c) A beneficiary designation that names a former spouse as beneficiary is invalid for purposes of this section unless the designation is made after the date of the divorce.
(d) A death benefit may not be paid under this section if, at the time of death, a death benefit annuity became effective.