(a) If any provision of this title requires the payment of interest on a tax claim or on an administrative expense tax, or the payment of interest to enable a creditor to receive the present value of the allowed amount of a tax claim, the rate of interest shall be the rate determined under applicable nonbankruptcy law. (b) In the case of taxes paid under a confirmed plan under this title, the rate of interest shall be determined as of the calendar month in which the plan is confirmed. (Added Pub. L. 109–8, title VII, § 704(a) , Apr. 20, 2005 , 119 Stat. 125 .) Statutory Notes and Related Subsidiaries Effective Date Section effective 180 days after Apr. 20, 2005 , and not applicable with respect to cases commenced under this title before such effective date, except as otherwise provided, see section 1501 of Pub. L. 109–8 , set out as an Effective Date of 2005 Amendment note under section 101 of this title .