40 ILCS 5/6-116

"Annuity": Annual payments for life, unless otherwise terminated under this Article, payable in 12 equal monthly installments beginning on the first day of the second month next following the date of the event upon which payment of annuity shall depend, shall occur and subsequent payments to be due and payable on the first day of each and every month thereafter, except that a smaller pro rata amount shall be paid for part of a month when the annuity begins after the first day of the month or ends before the last day of the month.