On and after , the Secretary—

((1)) may only enter into contracts for annual contributions regarding obligations financing public housing projects authorized by if such obligations are exempt from taxation under , or if such obligations are issued under and such obligations are exempt from taxation; and

((2)) may not enter into contracts for periodic payments to the Federal Financing Bank to offset the costs to the Bank of purchasing obligations (as described in the first sentence of ) issued by local public housing agencies for purposes of financing public housing projects authorized by .