Flannery O'Neill

Flannery O'Neill heads the firm's Tax practice. Her work focuses on partnership taxation, IRS controversy, and state and local tax matters for closely-held businesses and their owners. She structures operating agreements and joint ventures for tax-efficient distributions, represents clients through IRS examination and appeals, and handles Connecticut Department of Revenue Services audits and protests. She advises on § 1031 exchanges, partnership sales with § 751 "hot asset" implications, and the tax side of the Corporate group's M&A work — including rollover equity structuring, § 338(h)(10) elections, and the F-reorganization mechanics that have become standard in private-equity platform deals. O'Neill earned her LL.M. in Taxation from NYU School of Law in 2006, her J.D. from Boston College Law School in 2005, and her B.A. from Boston College in 2002. She joined Oak, Elm & Birch as an associate in 2006 and made partner in 2014. She took over as practice group head in 2020. Her path into tax law was unusual. Her grandfather, a longtime IRS trial attorney in the New England region, introduced her to the field at age twelve by handing her a copy of the Tax Court Rules and asking her opinion. She has said the field never stopped making sense. Her earliest substantive exposure to a § 754 election, she has said in CLE settings, happened at a family dinner. Within the Tax group, she leads a team of two associates and a paralegal, and has built a particular concentration in partnership tax disputes — an area that has grown sharply since the BBA centralized partnership audit regime took effect. She has been listed in *Best Lawyers in America* for Tax Law since 2020 and is a member of the American Bar Association's Tax Section and the Connecticut Bar Association's Tax Section Executive Committee. ## Publications - "Push-Out Elections Under the BBA: What Connecticut Practitioners Have Learned," *Connecticut Bar Journal*, Vol. 97 (2023). - Co-author, "State Tax Nexus After Wayfair: The Connecticut Experience Five Years In," *State Tax Notes*, April 2024. - Contributing author, *Connecticut Tax Practice Manual* (CBA-CLE Publications, 2022 revision) — chapter on partnership audit representation. - "The Partnership Representative's First Letter: Practical Drafting Under the BBA," *Journal of Passthrough Entities*, March 2022. ## Speaking & CLE - Co-chair, CBA Tax Section Annual Meeting, 2022 and 2024. - Annual presenter, "Connecticut DRS Audit Practice and Procedure," CBA Tax Section CLE, Hartford. - Panelist, "Partnership Tax After Soroban: Where We Are Now," NYU Institute on Federal Taxation, October 2024. - Faculty, annual ABA Tax Section midyear meeting, partnership tax workshop, 2021 and 2023. ## Beyond the Firm O'Neill's grandfather's framed IRS service certificate hangs in her office, next to her LL.M. diploma — a detail she declines to explain to first-year associates who ask. She lives in South Windsor with her husband and two children. She is a member of the Irish-American Business Association of Connecticut and, when time allows, a board member of her children's school's tuition-assistance committee. She is admitted in Connecticut and is a member of the Connecticut and American Bar Associations.