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Mark J. Brosnan

For the last 34 years, Mr. Brosnan has represented countless families, individual and institutional fiduciaries, businesses and financial institutions in matters ranging from estate planning and administration, Surrogate's Court litigation, real estate and business transactions, taxation and commercial litigation. As a result, Mr. Brosnan serves as a trusted advisor to many families and business owners throughout the State of New York.

Mr. Brosnan is admitted to practice law before the courts of the State of New York, and the United States District Court for the Southern and Eastern Districts of New York. Prior to and during law school, Mr. Brosnan was an accountant with a certified public accounting firm, where he gained experience as an auditor and tax practitioner.

From 1988 to 1994, Mr. Brosnan practiced law with a prominent Long Island firm and gained experience in real estate, banking and commercial litigation matters. In 1994, Mr. Brosnan co-founded and managed a law firm which established itself as one of Long Island's most reputable trusts and estates law firms.  During this period, Mr. Brosnan has handled several thousand estate planning and estate and trust administration matters, and prepared and filed thousands of estate tax and gift tax returns, fiduciary and individual income tax returns and fiduciary accountings. As a result, Mr. Brosnan has significant experience in estate planning, estate administration, real estate transactions, estate, gift and income taxation, and Surrogate’s Court litigation involving estates and trusts.

Mr. Brosnan has attained an “AV Preeminent®” rating from Martindale-Hubbell, which is the highest possible rating in legal ability and ethical standards.  Mr. Brosnan has extensive experience representing fiduciaries, beneficiaries, heirs and creditors in all types of Surrogate’s Court proceedings. From January 2001 through December 2011, Mr. Brosnan also represented the Public Administrator of Nassau County, a governmental agency which administers estates of Nassau County residents who die without wills and without known relatives, and which often involve litigation and kinship proceedings. He has been appointed by the Surrogate’s Courts as a guardian ad litem to represent infants and persons under a disability in numerous Surrogate’s Court proceedings. Mr. Brosnan has also authored several publications for the New York State Bar Association and charitable organizations, conducted estate planning seminars presented by various financial institutions, professional associations and charitable organizations.


St. John's University School of Law, Juris Doctor

St. John's University College of Business Administration,

Bachelor of Science in Accounting

Chaminade High School