(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.
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.