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Helen Buchanan


Energy | Investigations | Mergers and acquisitions | Tax | White collar defense and corporate crime |

Helen Buchanan is widely seen as one of the leading contentious tax practitioners in the market

Chambers & Partners 2023

Profile details

About Helen Buchanan

Helen is a highly experienced tax partner who has been advising clients on complex UK and international tax issues across all sectors for over 25 years.  

She leads the global contentious tax practice and her contentious caseload spans: high-value disputes relating to the deductibility of payments in the UK and internationally, including unallowable and main purpose challenges; disputes regarding where tax is paid by multinational groups, covering permanent establishment, residence, transfer pricing, diverted profit tax (DPT) and controlled foreign company (CFC) risks; state aid and treaty-based litigation and arbitration; employment taxes (including off-payroll working); capital gains and transfer taxes on corporate transactions; VAT and other indirect taxes; tax fraud; as well as cross-border tax warranty and covenant claims.

She has extensive UK and international litigation experience and, as a CEDR-accredited mediator, also has a strong track record of resolving cases out of court.

Alongside her contentious practice, Helen brings a practical and risk focussed approach to a wide range of corporate and finance transactions, including M&A, joint ventures, securitisations, leveraged finance, debt restructurings and corporate reorganisations.

Her sector experience includes energy and natural resources, infrastructure, TMT, pharmaceuticals, hospitality, retail and financial services.

She is ranked in Band 1 for contentious tax by Chambers & Partners.

Recent work

Contentious and Advisory

  • Advising various multinational clients on disputes relating to transfer pricing, valuation, diverted profits tax (DPT), controlled foreign company (CFC) and permanent establishment risk.
  • Advising a UK corporation on employment tax disputes affecting a substantial section of its workforce.
  • Advising multinational groups investing in Africa, Asia and the Middle East on tax disputes relating to capital gains tax, withholding taxes, VAT, branch profits tax, insurance and thin capitalisation.
  • Advising on insurance premium tax (IPT) and petroleum revenue tax (PRT) enquiries and disputes.
  • Advising an overseas government on aspects of its tax policy and on the settlement of a material tax dispute.
  • Advising on UK and international tax fraud investigations, including COP8 and COP9 investigations by HM Revenue and Customs (HMRC).
  • Advising various groups on "unallowable purposes" challenges relating to UK financing structures.
  • Advising on disputes relating to the deductibility of payments in the UK and internationally.
  • Advising on general anti-avoidance rule (GAAR) and recharacterisation challenges.
  • Advising on international tax and data protection issues involving the digital economy.
  • Advising on tax-related state aid challenges.


  • Advising Li & Fung on its $3.6 billion disposal of LF Logistics to Maersk;
  • Advising Yokohama Rubber on its €2 billion acquisition of Sweden’s Trelleborg Wheel Systems Holdings;
  • Advising OTPP on Allwyn AG’s acquisition of Camelot UK Lotteries Limited;
  • Advising PSP on an investment in Havram Wind AS with Sandbrook Capital;
  • Advising Alpek Polyester on its acquisition of OCTAL (a major producer of PET sheet and resin globally);
  • Advising RVU, the comparison division of ZPG and owner of Uswitch and, on its acquisition of Penguin Portals from Admiral Group plc. 
  • Advising OTPP on a sale of 30 per cent of its stakes in Bristol and Birmingham airports to Australia’s New South Wales Treasury Corp and investment firm Sunsuper Superannuation Fund.
  • Advising ArcLight Capital Partners on its acquisition of Total’s 100 per cent operated interest in the Frigg natural gas pipeline and the St Fergus Gas Terminal, and Total’s 67 per cent operated interest in the SIRGES gas pipeline.
  • Advising various UK-based groups on debt issuances and restructurings, including convertible and hybrid offerings and advising the Bank of England since the financial crisis.




Professional qualifications

  • CEDR accredited mediator