My passions — client service, tax policy and high-performing teams — are core to our National Tax Department ethos.

Colleen O’Neill

Partner, Tax, Ernst & Young LLP

Experienced tax professional, client server, speaker and author. Collaborative and empowering leader. Avid yogi. Mom of three.

Areas of focus

Colleen has nearly 30 years of experience serving tax clients and currently leads the US National Tax Department in Washington, DC. She has advised on tax-efficient global structures and the US taxation of cross-border transactions, including financing, acquisition, disposition, reorganization, integration, repatriation, supply chain matters and foreign tax credit planning.

In addition to speaking on various panels, Colleen has authored many tax articles and serves on the boards of the International Tax Institute, International Fiscal Association and Tax Council.

Colleen holds a Bachelor of Arts in Accounting and a Master of Business Administration in Taxation. She received a Juris Doctor, with honors, from the Georgetown University Law Center.

Colleen is a CPA and admitted to the NY state bar.

How Colleen is building a better working world

Colleen helps to build a better working world by embracing the motto “teamwork makes the dream work.” She actively seeks opportunities for EY tax professionals to demonstrate their many talents with clients, the government and within EY.

Colleen's latest thinking

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