Heather DiGregorio 1158

Heather DiGregorio


Add to contacts

University of Calgary, Bachelor of Laws, 2004 (Gold Medal for highest academic performance overall)

University of Calgary, Bachelor of Commerce, 1998

Bar admission: Alberta 2005
Practice areas:
Infrastructure and project development, Tax litigation, Tax


Heather is a leading tax practitioner in Canada who has been repeatedly recognized by her peers as a top tax expert in Canada.  With twenty years of experience, she brings her wide range of knowledge to solve complex problems for clients – whether they require tax planning and advisory work, or assistance in resolving disputes with the tax authorities.

Tax planning and advising experience:

  • Corporate tax planning across all major industries including natural resources, electricity generation, midstream companies, oil and gas services, pipelines, real estate development, agriculture, manufacturing, transportation and technology
  • Transactional experience advising on tax structures and considerations for buying and selling companies, businesses, and assets
  • Tax structuring complex, domestic and cross-border partnerships and joint ventures
  • Financing structures with taxable and tax-exempt entities and organizations

Dispute resolution experience:

  • Assisting with Canada Revenue Agency audits of all types, including comprehensive income tax audits, domestic and international matters, and aggressive tax avoidance auditors.
  • Negotiation and resolution of disputes with Canada Revenue Agency at audit and appeals levels.
  • Defending clients at all levels of Court, including Tax Court of Canada, Federal Court of Appeal and Supreme Court of Canada.



Professional involvement


Professional associations

  • Member, Law Society of Alberta
  • Member, Canadian Bar Association
  • Member, Calgary Bar Association
  • Member, Canadian Tax Foundation
  • Former Chair, Canadian Bar Association, Tax Specialists Section (Southern Alberta)
  • Former member of the Executive, Canadian Petroleum Tax Society


Heather has also presented at various conferences, panels, seminars, and other events, including:

  • A discussion of the recent Deans Knight Supreme Court Case, Tax Executives Institute Inc., Calgary Chapter March 2023 
  • When Audits Go Sideways: How to Hold the Canada Revenue Agency Accountable for its Actions?, Canadian Petroleum Tax Society, May 2018
  • Case Update, Canadian Tax Foundation Young Practitioners Series, 2017
  • Commercial Vehicles – Select Issues in Defining Legal Relationships, Canadian Tax Foundation Annual Conference, 2016
  • Case Law Update, Canadian Bar Association, Tax Specialists Subsection, 2016

Representative work

ARC Resources Ltd.'s $8.1 billion combination

Counsel to ARC Resources Ltd. in its $8.1 billion strategic Montney combination with Seven Generations Energy, resulting in ARC becoming Canada's largest condensate producer, third-largest natural gas producer and sixth-largest upstream energy company.

Deans Knight Income Corporation appeal to Supreme Court of Canada

Appeared at Supreme Court of Canada in precedent-setting tax case, Deans Knight Income Corporation v. His Majesty the King.  This high-profile dispute asked whether the general anti-avoidance rule in the Income Tax Act could apply to nullify a company's losses after it underwent a recapitalization and restart transaction.  With a taxpayer win at the Tax Court of Canada, which was subsequently overturned by the Federal Court of Appeal, the taxpayer appealed to the Supreme Court of Canada.  The appeal was heard on November 2, 2022. 

Graham Group’s acquisition of AECOM’s energy operations and maintenance business

Counsel to the Graham Group of Companies in the acquisition of the North American assets of AECOM’s Energy Operations and Maintenance Division. The acquisition positions the Graham Group as the third largest construction company in Canada and Western Canada’s largest industrial services company.

Greenfire Acquisition Corporation acquisition of Japan Canada Oil Sands Limited

Counsel to Greenfire Acquisition Corporation in its acquisition of all of the shares of Japan Canada Oil Sands Limited, which has a working interest in the Hangingstone facility in Alberta, for an undisclosed amount.

WestBlock Capital Inc. acquisition by LUXXFOLIO Holdings Inc.

Counsel to WestBlock Capital Inc., a cryptocurrency mining company, in its acquisition by LUXXFOLIO Holdings Inc., a digital infrastructure provider based in Canada for an undisclosed sum.

Whitecap Resources Inc's $300 million acquisition of Kicking Horse Oil & Gas Ltd.

Counsel to Whitecap Resources Inc. in its indirect acquisition of Kicking Horse Oil & Gas Ltd., a portfolio company of Quantum Energy Partners, for $300 million.

Alaris Equity Partners Income Trust $95 million financing

Counsel to Alaris Equity Partners Income Trust in a bought deal financing of 5,909,375 trust units for gross proceeds of $94,550,000.

Peloton's acquisition of Cevian Technologies

Counsel to Peloton in its acquisition of Cevian Technologies, a cloud-based software company, for an undisclosed amount.

​Whitecap Resources Inc.'s $560 million combination with TORC Oil & Gas Ltd.

Counsel to Whitecap Resources Inc. in its strategic business combination with TORC Oil & Gas Ltd. from Canada Pension Plan Investment Board and others for approximately $560 million.

Scoular Company's sale of its edible bean business for US $25 million

Canadian counsel to the Scoular Company, a large, privately-owned US agricultural commodities trading company, in the sale of its edible bean business, which included processing plants in St. Hilaire, Minnesota, U.S.; Plum Coulee and Morden, Manitoba; and receiving stations in Garske and Grafton, North Dakota, U.S., to Cooperative Elevator Co., for approximately US $25 million.

Alaris Royalty Corp. $100 million financing

Counsel to Alaris Royalty Corp. on its $100,000,000 financing of 5.5% senior unsecured subordinated debentures.

MEG Energy Corp.'s hostile tender offer from Husky Energy

Counsel to MEG, a Canadian oil sands producer, and its board of directors in response to the unsolicited tender offer by Husky Energy. Husky sought to acquire the entire share capital of MEG for approximately $6 billion.

NuVista Energy Ltd.'s acquisition of pipestone business of Cenovus Energy Inc.

Counsel to NuVista in the $625 million acquisition of the Cenovus Pipestone Partnership, which holds assets in the Pipestone area of Northwest Alberta.

NewAlta Corporation's $1 billion merger with Tervita Corporation

Counsel to NewAlta in the $1 billion merger with Tervita Corporation, a Canadian environmental solutions provider, in a stock swap transaction.

Enerflex Ltd.'s acquisition of Mesa Compression, LLC

Counsel to Enerflex Ltd., through the U.S. entity Enerflex Energy Systems Inc., in its US$106 million acquisition of U.S. based contract compression business, Mesa Compression, LLC.

Sale of Marathon Oil Canada Corporation to CNRL

Counsel to Marathon Oil Corporation in the US$2.5 billion sale of Marathon Oil Canada Corporation to Canadian Natural Resources Limited and Shell Canada Energy.

Spur Resources Ltd.'s $407 million acquisition

Counsel to Spur Resources Ltd. in the $407.5 million acquisition by Tamarack Valley Energy Ltd.

Tourmaline Oil Corp.'s $1.3 billion acquisition of energy assets

Counsel to Tourmaline Oil Corp. in the $1.37 billion acquisition of strategic assets located in the Alberta Deep Basin and the north east British Columbia Gundy area from Shell Canada Energy.

Inter Pipeline Ltd.'s $600 million public offering

Counsel to Inter Pipeline Ltd. in a $600 million public offering of 22,430,000 subscription receipts.

Axia NetMedia Corporation's $272 million acquisition

Counsel to Axia NetMedia Corporation in the $272 million acquisition by Partners Group in a going private transaction completed by plan of arrangement.

Yoho Resources Inc. going private transaction

Counsel to Yoho Resources Inc. in the $30.5 million going private transaction led by One Stone Energy Partners LP.

$595 million energy asset acquisition by Whitecap Resources Inc.

Counsel to Whitecap Resources Inc. in the $595 million acquisition of premium oil assets in southwest Saskatchewan from Husky Energy Inc.

PrairieSky Royalty Ltd.'s $1.8 billion asset acquisition

Counsel to PrairieSky Royalty Ltd. in $1.8 billion acquisition of royalty assets from Canadian Natural Resources Limited.

Carmel Bay Exploration Ltd.'s line of credit from Quantum Energy Partners

Counsel to Carmel Bay in the $200 million equity line of credit established from Quantum.

Ag Growth International Inc.'s $221 million acquisition

Counsel to Ag Growth International Inc. in the $221 million acquisition of the Westeel division of Vicwest Inc.

Freehold Royalties Ltd.'s $373 million public offering

Counsel to Freehold Royalties Ltd.in its $373 million public offering of 20,700,000 common shares and the $33 million private placement of 1,833,334 common shares.

Mullen Group Ltd. acquisition of Gardewine Group Limited Partnership

Counsel to Mullen Group Ltd. in the $172 million acquisition of Manitoba-based Gardewine Group.

Progress Energy Canada Ltd.'s acquisition of energy assets

Counsel to Progress Energy Canada Ltd. in the $1.5 billion acquisition of part of Talisman Energy Ltd.'s Montney acreage in northeast British Columbia.

Baytex Energy Corp.'s $1.5 billion financing

Counsel to Baytex Energy Corp. in its $1.5 billion public offering of 38,433,000 subscription receipts.

$5.2 billion acquisition of Progress Energy Resources Corp.

Counsel to Progress Energy Resources Corp. in the $5.2 billion acquisition by PETRONAS, the Malaysian national oil company.

Progress Energy Resources Corp.'s sale and joint venture with PETRONAS

Counsel to Progress in the $1.1 billion sale of 50% working interest in Montney shale assets in Foothills of north eastern British Columbia to PETRONAS, the Malaysian national oil company, and the formation of an upstream joint venture to develop the gas assets as well as a downstream LNG Export Project Joint Venture pursuant to which they plan to build and operate a major LNG export facility.

Sale of Decisive Farming Corp.

Counsel to Decisive Farming Corp in the acquisition by TELUS Agriculture Solutions Inc.

US Development Group LLC's joint venture with Gibson Energy

Counsel to US Development Group LLC in its 50/50 joint venture with Gibson Energy to advance the financing, development and construction of a Diluent Recovery Unit in Hardisty, Alberta.

Power company's bid to acquire Regional Power Inc.

Advising a power development company on its due diligence and bid to acquire Regional Power Inc., a corporate group with 106 MW of hydroelectric assets in BC and Ontario from ManuLife Financial Corporation.

TriWest Capital Partners investment in HPC Energy Services Ltd.

Counsel to HPC Energy Services Ltd. in a Plan of Arrangement whereby TriWest Capital Partners acquired a majority interest in HPC Energy Services Ltd.

Advising Deans Knight on a tax dispute

Counsel to Deans Knight Income Corporation in a case that involves whether the deduction of tax attributes can be properly denied by the CRA on the basis of the general anti-avoidance rule in the Income Tax Act (Canada). (Deans Knight Income Corporation v. Her Majesty the Queen)

International Petroleum Corporation acquisition of oil and natural gas assets from Cenovus Energy Inc.

Counsel to International Petroleum Corporation in the acquisition of oil and natural gas assets in Suffield and Alderson areas of southern Alberta from Cenovus Energy Inc. for proceeds of $512 million plus an additional deferred contingent amount of $36 million

Power development company's acquisition of green power

Advising a power development company on a limited partnership and contract for differences with a corporate investor that was interested in acquiring green power from an independent wind project as part of its efforts to reduce its carbon footprint.


Recent honours and recognition

Recognized in Best Lawyers Canada in Tax Law (2020-2023)

Named by the Canadian Legal Lexpert Directory as a leading lawyer in corporate tax (2018, 2020-2024)

Named in Lexpert's Special Edition on Canada's Leading Energy Lawyers (2020)

Recognized by the Legal 500 Canada as a recommended tax lawyer (2018-2019)