Payment of supplement.

Any supplement due and payable under this act shall be paid by the department or under the direction and control of the department, based on information furnished by the retired member, or a joint annuitant, and the administrator of the system under which retirement benefits are being paid, beginning on the first day of the month coincident with or next following the later of the effective date of this act and the date of approval of the application for supplement by the department, and payable thereafter on the first day of each month in the normal or optional form in which retirement benefits under the applicable system are being paid; provided, however, that if application for supplement is made subsequent to December 31, 1967, not more than 6 retroactive monthly supplements shall be paid.