From the allotment of each State for a fiscal year under section
796e of this title, the State shall be paid the Federal share of the expenditures incurred during such year under its State plan approved under section
796d–1 of this title. Such payments may be made (after necessary adjustments on account of previously made overpayments or underpayments) in advance or by way of reimbursement, and in such installments and on such conditions as the Commissioner may determine.