A pension granted under the provisions of the act, to which this act is amendatory and supplementary, shall be effective only on the first day of a month, shall be paid in equal monthly installments, and shall not be decreased, increased, revoked or repealed, except as otherwise provided by the statutory law. No pension shall be due to a retirant or beneficiary unless it constitutes a payment for an entire month; provided, however, that a pension shall be payable for the entire month in which the retirant or beneficiary dies.
N.J.S. § 43:16-1.2