Area of Focus
Washington National Tax Tax controversy

Marissa Lenius

Senior Manager

About Marissa

Marissa Lenius is a senior manager in the tax controversy group in RSM US LLP’s Washington National Tax practice.


Marissa brings over a decade of experience as an attorney with the IRS Office of Chief Counsel to her role in guiding RSM clients through tax controversy matters. As an IRS attorney, she advised IRS examiners in both procedural and substantive matters pertaining to federal tax examinations and claims for refund.

She also regularly participated in conferences and alternative dispute resolution proceedings, such as Fast Track Settlement and Post Appeals Mediation, with the IRS Office of Appeals. In addition, Marissa represented the IRS in cases before the United States Tax Court. In her role as senior counsel, Tax Exempt and Government Entities Division, she developed deep knowledge of federal employment taxes and exempt organization matters.

Marissa has also reviewed, developed and delivered many training sessions on federal tax substance and procedure, including topics such as worker classification and section 530 relief from employment taxes, summons drafting and enforcement, accountable plans and fringe benefits, and employment tax consequences of settlements and judgments.

Marissa has a heart for public service; she taught ninth grade English in Baltimore City as a Teach for America corps member, has served as a guardian ad litem for youth in state care and is currently a foster parent with her husband. She spends her free time baking and wrangling kids. 

Professional affiliations and designations

  • United States Tax Court, admitted to practice
  • Florida Bar Association, tax section


  • Juris Doctor (magna cum laude), University of Maryland School of Law
  • Master of Arts, teaching, Johns Hopkins University
  • Bachelor of Arts; English, linguistics (magna cum laude); University of Florida