Section 13. (1) Amounts, Conditions and Intervals of Payments. — (a) Payments under any annuity, pension or retirement allowance provided for under this chapter and in effect on December thirty-first, nineteen hundred and forty-five, shall continue to be due and payable in the same amounts, under the same conditions and at the same intervals of time as were in effect on such date, except that such payments to members of the teachers' retirement system shall be due and payable monthly, and the teachers' retirement board is authorized to increase on December first, nineteen hundred and fifty-one, if necessary, the annual rate of the retirement allowance of any such member of the teachers' retirement system by an amount not exceeding sixteen cents to provide equal monthly instalments of annuity and pension.

(b) Payments under any annuity, pension or retirement allowance provided for under sections one to twenty-eight inclusive and becoming effective after December thirty-first, nineteen hundred and forty-five, shall be due and payable for the month on the last day of each month during the continuance of such annuity, pension or retirement allowance, as the case may be. The yearly amount of any such annuity, pension or retirement allowance shall be computed to the nearest cent which makes such amount an integral multiple of twelve cents. The amount of each full monthly payment shall be one twelfth of the corresponding yearly amount and the first such full payment shall be due and payable on the last day of the month following the month in which falls the date as of which such annuity, pension or retirement allowance becomes effective. If such effective date is a day other than the last day of the month in which it falls, a pro rata payment shall be allowed for the period following such date and ending with such last day. No payment under any such annuity, pension or retirement allowance shall be made for any period prior to the day next following the date for which such member last received regular compensation for his employment in the public service. Except as otherwise specifically provided for in sections one to twenty-eight inclusive, monthly payments shall be made during the lifetime of the person upon the continuance of whose life the payments depend and shall cease with the last full monthly payment due prior to the death of such person; provided, that a pro rata payment shall be allowed for that portion of the month in which such death occurs which has elapsed up to and including the date of death.

(c) A retirement board may require a member entitled to receive a retirement allowance to designate a financial institution to which shall be directly deposited any payments under any annuity, pension or retirement allowance.

(2) Settlement of Small Allowances in One Sum. — (a) Any member otherwise entitled to receive a retirement allowance under the provisions of sections one to twenty-eight inclusive, the normal yearly amount of which would be less than three hundred and sixty dollars, shall, in lieu of receiving such allowance, be paid the amount of his accumulated total deductions as of the date such allowance would otherwise become effective.

(b) Any member otherwise entitled to receive a retirement allowance under the provisions of sections one to twenty-eight inclusive, the normal yearly amount of which would be less than six hundred dollars but not less than three hundred and sixty dollars, shall, in lieu of receiving such allowance, be paid the amount of his accumulated total deductions as of the date such allowance would otherwise become effective if his written request therefor as provided for in subdivision (1) of section eleven is filed with the board on a prescribed form prior to the date the first payment of such allowance would otherwise become due.

(c) Nothing herein shall entitle any member who is paid the amount of his accumulated total deductions under the provisions of this subdivision to remain in service.