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Mark Tonkovich
Mark Tonkovich (he, him, his) Partner | Toronto

About Mark

Mark leads the Tax Controversy and Litigation group. His work focuses on resolving tax and tax-related public law disputes, and he represents many of Canada's and the world's largest and most sophisticated businesses. He has particular expertise in proactively analyzing and advising on tax litigation risks, navigating sensitive tax audits, negotiating with federal and provincial tax authorities, and litigating tax assessments and CRA administrative actions. Described by clients as "the consummate professional" in Chambers and Partners' 2020 Guide to Canada's Leading Lawyers for Business, Mark develops and executes comprehensive and practical strategies for resolving tax disputes as efficiently and favourably as possible, both in and out of the courtroom.

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. The Federal Court of Appeal observed 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 Blakes, 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.

Select Experience
  • Frontline or behind-the-scenes representation on a large number and variety of complex tax audits, including in the context of reviews by the Canada Revenue Agency's (CRA) Aggressive Tax Planning Division, pertaining to issues such as transfer pricing, the foreign affiliate regime, entitlement to benefits under Canada's tax treaties, the reporting of offshore assets/investments, employee/independent contractor classification, and the scientific research and experimental development (SR&ED) program

  • Administrative appeals relating to matters as diverse as foreign accrual property income, non-resident withholding tax, payments in respect of intellectual property, the thin capitalization rules, errors in the presentation of financial information, income vs. capital characterization issues, federal sales tax and the financial service exemption, provincial sales tax on insurance products, and the scope and validity of provincial income tax assessments

  • Trial-level tax disputes involving the general anti-avoidance rule (GAAR), the taxation of foreign affiliates, transfer pricing adjustments, foreign entity characterization, the SR&ED program, and the tax consequences of employee/shareholder fraud

  • Appellate-level cases concerning the GAAR, business vs. property income issues, employer-provided taxable benefits, and the implementation of the provincial reassessment waiver regime

  • Applications for judicial review concerning failures by the CRA to issue timely assessments of federal income tax, compelling the refund of erroneously-remitted Part XIII withholding tax, disputing the validity of CRA audit requirements, challenging the CRA's refusal to provide relief from double taxation under the Canada-US Tax Treaty, and navigating the intersection of employment insurance and bankruptcy law

  • Counsel in the first CRA private inquiry (under s. 231.4 of the Income Tax Act) to be held in the past two decades

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

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

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

  • Voluntary disclosure submissions concerning a complex web of cross-border transactions involving dozens of legal entities, offshore asset reporting issues, and substantial errors under various provincial sales tax regimes

  • Post-transaction opinions on specific tax risks, focusing on the viability of client tax positions and the proactive management of litigation risks and other sensitive matters

Awards & Recognition

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

  • The Canadian Legal Lexpert Directory – 2021–2024 (Consistently Recommended: Litigation – Corporate Tax)

  • Chambers Global: The World's Leading Lawyers for Business – 2021–2024 (Tax: Litigation – Canada)

  • Chambers Canada: Canada's Leading Lawyers for Business – 2020–2024 (Tax: Litigation – Nationwide)

  • The Legal 500 Canada – 2020–2024 (Tax Law)

  • The Best Lawyers in Canada – 2019–2024 (Tax Law)

  • ITR World Tax – 2017–2024 (Highly Regarded – Tax Controversy)

  • Thomson Reuters Stand-out Lawyers – Independently Rated Lawyers – 2023–2024 (As nominated by senior in-house counsel)

  • Lexpert Special Edition: Litigation 2023

  • Lexpert Rising Stars: Leading Lawyers Under 40

  • Lexpert Special Edition on Canada's Leading Litigation Lawyers 2022

Professional Activities

Mark is a frequently published author. He has written or co-written dozens of articles on Canadian tax matters, including in the peer-reviewed Canadian Tax Journal and the National Journal of Constitutional Law, as well as in several trade publications. He also sits on the editorial board of Tax Litigation, a Federated Press journal.

Mark is the chair of the Tax Court Bench and Bar Committee, a board member of the Toronto Centre CRA & Tax Professionals Group, and a past chair of the Ontario Bar Association's Taxation Law Section. He is also a member of the Canadian Tax Foundation, The Advocates' Society, the Canadian Bar Association, the Canadian Petroleum Tax Society, the International Fiscal Association, the Halton County Law Association, and the Ukrainian Canadian Bar Association.

Mark regularly speaks at events for tax professionals and has appeared as an invited witness before the House of Commons Standing Committee on Finance.

Mark has also provided many hundreds of hours of pro bono public-interest representation to select organizations and low-income individuals. He is a founding board member and serves as secretary of the non-profit Making the Shift Inc., a youth homelessness social innovation lab that has been granted $17.9 million in funding from the Canadian government to address and prevent youth homelessness. Mark also volunteers as a judge for a variety of moot court competitions (including the Bowman National Tax Moot, the Canadian rounds of the Jessup International Moot, and the OBA/OJEN High School Mock Trial Competition).

Professional Appearances
  • Moderator : Judges' Panel
    Celebrating the Tax Court of Canada: 40 Years of Service to Canadians, Canadian Tax Foundation, Toronto, Ontario, October 6, 2023.
  • Co-presenter : How to Select and Prepare Your Witness
    The Advocates’ Society’s Seminar Tax Litigation: The Effective Witness, Toronto, Ontario, January 18, 2023.
  • Co-presenter : Professionalism and Ethical Obligations: Managing Tricky Transactions and interactions
    Ontario Bar Association’s Annual CPD Seminar: Professionalism and Ethical Issues for Tax Lawyers, Toronto, Ontario, December 8, 2022.
  • Co-presenter : Budget 2021 Highlights – Expanded CRA Audit Authority and Tax Avoidance Matters TEI Vancouver
    Blakes TEI Tax Seminar, Tax Executives Institute, June 2021.
Media Activities
  • Quoted : Comparing the general and limited programs
    Interviewed by Margaret Craig-Bourdin, CPA Canada, February 9, 2023.
  • Quoted : How and when to use the CRA’s Voluntary Disclosures Program
    Interviewed by Margaret Craig-Bourdin, CPA Canada, February 9, 2023.
  • Featured : Alumni Spotlight
    Interviewed by Osgoode Professional Development, Osgoode Hall Law School, December 19, 2022
  • Quoted : What to do when your tax client disagrees with the CRA
    Interviewed by Margaret Craig-Bourdin, CPA Canada, September 8, 2022.
  • Quoted : The CRA objections process: when should CPAs call in a lawyer?
    Interviewed by Margaret Craig-Bourdin, CPA Canada, September 8, 2022.
Admitted to the Ontario Bar – 2009
LLM (Tax), Osgoode Hall Law School – 2014
LLB (With Distinction, Lord Beaverbrook Scholar), University of New Brunswick – 2008
BA, University of Guelph – 2005
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