"In light of the comments received, the Treasury Department and the IRS have concluded that transition rules to phase in the three-year period provided in these final regulations are appropriate. Accordingly, the final regulations provide that for the first taxable year beginning after December 31, 2013, an organization's MLR will be computed on a one-year basis.... The Treasury Department and the IRS continue to consider whether, and, if so, how to permit organizations to address de minimis failures to satisfy the MLR under section 833(c)(5).... [T]he Treasury Department and the IRS have concluded that a change in an organization's eligibility for treatment under section 833 solely by reason of section 833(c)(5) will not be treated as a material change in the operations of such organization or in its structure for purposes of section 833(c)(2)(C)."