paid in cash
(f) Paid in cash. The term paid in cash means a payment in United States dollars that (1) Is made by cash, check, cashier's check, money order, wire transfer, automated clearing house (ACH) transfer, or other bank transfer of immediately available funds; (2) Is made within the period beginning on the first day of the eligible taxpayer's taxable year during which a specified credit portion is determined and ending on the due date for completing a transfer election statement (as provided in 1.6418-2(b)(5)(iii)); and (3) May include a transferee taxpayer's contractual commitment to purchase eligible credits with United States dollars in advance of the date a specified credit portion is transferred to such transferee taxpayer if all payments of United States dollars are made in a manner described in paragraph (f)(1) of this section during the time period described in paragraph (f)(2) of this section.