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100% Partners Ranked by Best Lawyers or Super Lawyers

For more than 75 years, Kostelanetz LLP has built a global reputation as a law firm of choice for clients facing high-stakes controversies and negotiations with government agencies.

Practice Areas

The firm’s practice is comprised of criminal, regulatory, and civil litigation matters. The firm’s clients have included Fortune 500 corporations, closely-held corporations, securities traders, investment advisers, public officials, and well-known individuals in the world of business as well as the arts and entertainment industry. In addition, the firm regularly represents clients in their estate planning and wealth management matters.

Civil Tax Controversies
& Trials

Criminal Tax Investigations & Prosecutions

White-Collar Criminal Defense & Government Investigations

International Tax Controversies

Estate and Tax Planning – Estate and Trust Administration

Internal Investigations

Tax Promoter Audits and Investigations

Civil Dispute Resolution – Complex Commercial Litigation

Government Procurement & Contracting

Appellate Litigation

Transactional Tax Planning

Voluntary Disclosures

Kostelanetz LLP nyc skyline

Globally Recognized

 

Kostelanetz LLP attorneys have unparalleled experience in tax controversy, tax fraud, government investigations, and white-collar criminal defense. Important parts of the firm’s practice also include tax and estate planning, commercial litigation, and government procurement and contracting. 

Results Oriented

 

Kostelanetz LLP and its attorneys have been honored and recognized for their skill and work by major, independent national and international legal rankings agencies, including Chambers USA, The Legal 500, Best Lawyers, and Super Lawyers.

Kostelanetz LLP dc supreme court

Knowledge Base

Blog topics covering Inbound Marketing, Responsive Web Design, lead generation, UX, and SEO

IRS Vow to Amp Up Audits Puts Tax-Exempt Entities in Crosshairs

Kostelanetz partners Karen Kelly and Melissa Wiley author Bloomberg Law article titled “IRS Vow to Amp Up Audits Puts Tax-Exempt Entities in Crosshairs.”

Gray Proctor Quoted in Law360 Article on Jarkesy Ruling and Tax Controversy

Kostelanetz attorney Gray Proctor was quoted in a Law360 article titled “4 Ways Justices' Jarkesy Ruling Could Affect Tax Controversy.”

Kostelanetz Named ‘Law Firm of the Year’ for Tax Controversy Litigation by Best Law Firms

Kostelanetz LLP has been selected as ‘Law Firm of the Year’ for Litigation and Controversy – Tax in the 2026 edition of Best Law Firms®.