(a) After the initial one or two payment months of assistance under § 233.24, the amount of each subsequent month's payment shall be computed retrospectively, i.e., shall be based on earned and unearned income received in the corresponding budget month.

(b) In these subsequent months, other factors of need which affect the amount of the assistance payment may also be based on circumstances in the corresponding budget month, or they may be based on circumstances in the payment month.

(c) For the first month in which retrospective budgeting is used, a State shall not consider income received by the recipient before the date of application. When a person reapplies during the same month in which a termination became effective, the State may consider income received before the date of application.