94-411-414 Me. Code R. § 4
If the benefit selection form for a beneficiary of a vested member who has a choice between a lump-sum payment, or a lifetime benefit is not received by MainePERS on or before October 1 of the calendar year following the year of the member's death, the benefit will default to the monthly benefit option as described in 5 M.R.S. §17953(5-B) and § 18553(5-B). The effective date of the monthly benefit will be no later than December 31 of the calendar year following the year of the member's death. Once a distribution is made under this Section, the beneficiary may not change the manner in which the benefits are distributed.
If the sole beneficiary is the member's spouse, the default benefit under this section will be delayed until December 31 of the year the member would have turned 72.
94-411 C.M.R. ch. 414, § 4