Mark Tonkovich
Partner | Toronto
Toronto: 416-863-5258

For the past decade, Mark’s practice has focused exclusively on resolving tax and related public law disputes. He has expertise in a wide range of areas, including with respect to the analysis of tax assessment and litigation risks, audit management and defence, negotiation with federal and provincial tax authorities, and tax-related civil litigation.

An exceptional litigator, Mark has successfully represented many clients in administrative appeals and before federal and provincial courts, including the Tax Court of Canada, the Federal Court, the Federal Court of Appeal, the Ontario Superior Court of Justice, the Court of Appeal for Ontario, the Court of Appeal of Alberta, and in resisting leave to appeal before the Supreme Court of Canada. For instance, the Federal Court of Appeal noted as follows in a 2013 judicial review application: "In exemplary fashion, Mr. Tonkovich untangled a confusing body of evidence and argument, discerned the most important legal issues, and effectively presented submissions that were of significant assistance to the Court in the efficient resolution of this case."

Before joining the Firm, Mark was a tax partner at a prominent international law firm. Prior to that, he was a government tax litigator with the Department of Justice and a judicial clerk at the Federal Court of Appeal.

  • Trial-level tax disputes concerning the general anti-avoidance rule (GAAR), the taxation of foreign affiliates, transfer pricing adjustments, the scientific research and experimental development (SR&ED) program, and the tax consequences of employee fraud

  • Appellate-level cases concerning the GAAR, employer-provided taxable benefits, and the implementation of the provincial reassessment waiver regime

  • Appellate-level judicial intervention on behalf of the Canadian Bar Association concerning fundamental precepts of solicitor-client privilege

  • Applications for judicial review concerning the refusal of the Canada Revenue Agency (CRA) to provide relief from double taxation under the Canada-US Tax Treaty, its failure to issue timely assessments of federal income tax, the intersection of employment insurance and bankruptcy law, and compelling a refund of erroneously remitted Part XIII withholding tax

  • Provincial rectification proceedings to correct substantial transactional errors in a cross-border hybrid refinancing plan

  • Administrative appeals relating to foreign affiliates, withholding tax and payments in respect of intellectual property, and to the scope and validity of provincial income tax assessments

  • Submissions to the CRA's Transfer Pricing Review Committee defending against the application of transfer pricing penalties

  • Analyses of potential administrative and judicial appeals pertaining to contractual break fees, the taxation of mining profits and accounting errors in the presentation of financial information

  • Both frontline and behind-the-scenes guidance on a large number and variety of tax audits, including in the context of reviews by the CRA's Aggressive Tax Planning Section, the foreign affiliate regime, transfer pricing issues, employee/independent contractor classification and the SR&ED program

  • Submissions under the CRA's Voluntary Disclosure Program for a complex web of cross-border transactions involving over three dozen legal entities


Mark is recognized as a leading tax lawyer in the following publications:

  • International Tax Review’s World Tax 2019 – Highly Regarded (Tax Controversy)

  • The Best Lawyers in Canada 2019

  • International Tax Review's Tax Controversy Leaders Canada – 2017 and 2018

Show Past:
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Co-author: Future Law and Alternative Facts in the GAAR Analysis
Tax Litigation, Vol. 21, Issue 1, p. 6, Federated Press, 2018.
Co-author: After IGGillis Holdings: Protecting privilege when giving common legal advice
CBA National, March 26, 2018.
Co-author: FCA Rules CRA Cannot Force Taxpayers to Self-Audit on Uncertain Tax Positions
Taxation Law Section Newsletter, Ontario Bar Association, May 15, 2017.
Author: Theft by Owners or Senior Employees: Deductibility of Losses
Canadian Tax Focus, Vol. 6, Issue 1, pp. 1-2, 2016.
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Co-presenter: Transfer Pricing – Law and Practice
International Fiscal Association YIN Seminar, IFA Canada, March 2019.
Co-presenter: Current Cases Seminar
Ontario Tax Conference, Canadian Tax Foundation, October 2018.
Mentor: Speed Mentoring – Practical Advice on Succeeding as a Young Tax Lawyer
Taxation Law Section Seminar, Ontario Bar Association, October 2018.
Panellist: Best Practices to Deal with Canadian Tax Authorities and Audits
Canadian Tax Workshop for US Companies, Council on State Taxation, September 2017.
Panellist: Need to File an Appeal – Procedures to Object and Appeal Canadian/Provincial Tax Assessments and Customs/Duties (Including Input GST)
Canadian Tax Workshop for US Companies, Council on State Taxation, September 2017.
Chair: Year-End Address
Taxation Law Section Year-End Seminar, Ontario Bar Association, June 2017.
Speaker: Tax Challenges in Taking Your Business International
Trade Accelerator Program, Toronto Region Board of Trade, March 2017.
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Quoted: Federal Court of Appeal gives guidance to CPP filing obligations of retired business partners
Interviewed by Terry Davidson, The Lawyer’s Daily, June 18, 2018.
Quoted: Federal Court of Appeal clarifies reach of solicitor-client privilege
Interviewed by Amanda Jerome, The Lawyer's Daily, March 14, 2018.
Quoted: The CBA’s intervention on common interest privilege
Interviewed by Yves Faguy, CBA National Magazine, October 5, 2017.
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