The Social Security Act requires the OIG to notify the HHS Secretary if the average sales price (ASP) for a particular drug exceeds the drug's average manufacturer price (AMP) or widely available market price (WAMP) by a threshold, currently set at 5%. If that threshold is met, the Secretary is authorized to disregard the drug’s ASP and substitute the lesser of the WAMP or 103% of AMP. CMS’s 2012 Medicare physician fee schedule rule specified the circumstances under which AMP-based price substitutions will occur beginning January 2012 (although CMS has not announced any such substitutions to date, due in part to concerns about a developing drug shortage situation). According to a recent OIG report comparing fourth quarter 2011 ASPs and AMPs, reimbursement for 14 drugs would have been reduced in the second quarter of 2012, saving an estimated $4.6 million if CMS exercised its price substitution policy (the savings would have been higher if additional drugs with partial AMP data were included).