Mary Anne McMahon, LLB

Mary Anne is a national advisor with Ernst & Young in Ottawa, where she is the leader of Ernst & Young's indirect tax practice in that office. Mary Anne coordinates and provides national advice on indirect tax matters including GST/HST, excise and customs duty, provincial taxes and softwood lumber. A lawyer, she is a member of Couzin Taylor LLP, a law firm associated with Ernst & Young.

Prior to joining Ernst & Young, Mary Anne enjoyed a career of more than 30 years with Justice Canada and the Canada Revenue Agency (CRA). As a general counsel with the Legal Services Branch of the CRA she led the indirect tax practice in that office, served as a legal advisor to the Minister of National Revenue, the Commissioner of Revenue and senior CRA officials, and served as legal counsel to the CRA Board of Management. Mary Anne is the associate editor of Chartered Professional Accountants (CPA Canada)'s Commodity Tax News.


Canada is celebrating its 150th anniversary. We’re celebrating you, Canadian CPAs. Tell us why you’re proud to be a Canadian CPA. Then watch for our big celebration in July.

Gain practical organizational insights and learn from industry experts at this annual event for not-for-profit financial leaders.