Pfizer, Allergan Scrap $160 Billion Deal After U.S. Tax Rule Change Posted by April 6, 2016 Leave a comment on Pfizer, Allergan Scrap $160 Billion Deal After U.S. Tax Rule Change The merger would have allowed New York-based Pfizer to cut its tax bill by an estimated $1 billion annually by domiciling in Ireland, where tax rates are lower.