"[CMS] will reconcile 2014 benefit year cost-sharing reductions for all issuers in April 2016, rather than in April 2015.... [M]any issuers using the simplified methodology are falling short of the 12,000 member month credibility threshold for a particular subgroup more frequently than anticipated -- and will be required to use the simplified 'AV methodology,' which may yield inaccurate estimates of cost-sharing reductions provided to eligible enrollees in those plans.... [M]any issuers using the standard methodology are continuing to have difficulty upgrading their systems in time for reconciliation of advanced payments of cost-sharing reductions ... putting at risk the accuracy of those calculations. Therefore, to enhance the accuracy of reconciliation of reductions in out-of-pocket expenses that issuers provided to eligible ... enrollees, CMS will permit issuers that selected the simplified methodology to switch to the more accurate standard methodology, and will reconcile 2014 benefit year cost-sharing reductions for all issuers beginning on April 30, 2016."