On August 4, 2015, the long-awaited final rule from CMS implementing the Affordable Care Act changes to the calculation of Average Manufacturer Price (AMP) went over to the Office of Management and Budget (OMB).  OMB has up to 90 days to review a rule before it is published.  As such, we anticipate the final rule will be issued before November 4, 2015.  Manufacturers should stand ready to promptly analyze the content of final rule, and AMP methodologies and Government Pricing systems will need to be modified and updated to ensure their products’ AMP calculations comply with the final rule.  In addition, pharmacies should closely watch for the release of the final AMP rule, as CMS has said it plans to finalize draft AMP-based federal upper limits, which will serve as the upper limit on reimbursement for multiple source generic drugs, following release of the final rule.  Depending on the articulated parameters for calculating AMPs set forth by CMS in the final rule, reimbursement for multiple source generic drugs could increase or decrease for certain therapeutic classes of drugs.