Cian O'Sullivan

Director, BDO Dublin


Cian is a Director in the Taxation department. He has over 10 years' experience in advising on a range of corporate tax matters.


Cian joined BDO in 2008. Since joining the firm, he has worked across a wide range of sectors on numerous tax planning issues, including corporate reorganisations and restructures, mergers & acquisitions and property related matters, for both domestic and international clients. Cian has also worked on a number of substantial R&D tax credit claims.

In recent years, Cian has undertaken tax due diligence assignments for significant transactions and has carried out tax risk assurance checks for a number of large corporates. 

Cian is a Fellow of Chartered Accountants Ireland and an Associate of the Irish Taxation Institute. He has a BA in Accounting and Finance and an MBS in Accounting from DCU. Cian has also written articles for both Accountancy Ireland and Tax.Point.