Sean McMahon

Sean McMahon


LLM, Boston University School of Law
JD, New England School of Law
BA, Fairfield University


D. Sean McMahon is a former Senior Attorney with the IRS Office of Chief Counsel and a former Special Assistant United States Attorney for Massachusetts and New Hampshire where he was responsible for tax cases. Sean has more than fifteen years of experience investigating and defending IRS and state tax matters and excels at resolving difficult and complex tax disputes. He counsels clients through examinations and liability disputes and, when necessary, takes disputed issues to court. Sean has been named to the Massachusetts Super Lawyers list in the area of tax law.

As a former IRS attorney, Sean offers clients unique insights on the real risks presented in disputes with the IRS and planning for complex transactions. He advises clients on the tax considerations of corporate, real estate, partnership, securities and option transactions. Sean also has extensive experience assisting individuals with foreign transaction reporting and penalty disputes, including foreign bank accounts and FBAR requirements.