For the month an individual reestablishes eligibility after a month of ineligibility, an SSI payment will be made on or after the day of the month on which the individual becomes reeligible to receive benefits. In all other months, a payment will be made on the first day of each month and represents payment for that month. If the first day of the month falls on a Saturday, Sunday, or legal holiday, payments will be made on the first day preceding such day which is not a Saturday, Sunday, or legal holiday. Unless otherwise indicated, the monthly amount for an eligible couple will be divided equally and paid separately to each individual. Section 416.520 explains emergency advance payments.
20 C.F.R. §416.502