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Helen Buchanan



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

Chambers & Partners 2021

Profile details

About Helen Buchanan

Helen leads the firm’s London tax practice and global tax disputes practice, advising clients on complex UK and international tax issues across all sectors.

Her contentious caseload spans diverted profits tax, transfer pricing, unallowable purposes and other corporate tax disputes, permanent establishment and controlled foreign company (CFC) issues, employment taxes (including off-payroll working), capital gains and transfer taxes, IPT, VAT and tax fraud.

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 and Asia on tax disputes relating to capital gains tax, withholding taxes, VAT, branch profits tax 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.
  • Advising various groups on "unallowable purposes" challenges relating to UK financing structures.
  • Advising on international tax and data protection issues involving the digital economy.
  • Advising on tax-related state aid challenges.


  • Advising RVU, the comparison division of ZPG and owner of Uswitch and, on its acquisition of Penguin Portals from Admiral Group plc. 
  • Advising Ontario Teachers’ Pension Plan 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 CK Hutchison Holdings on its Italian mobile telecoms joint venture with VimpelCom.
  • 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 for £585m.
  • Advising the Bank of England throughout the financial crisis, including on the special liquidity scheme, discount window facility and other measures.
  • Advising various UK-based groups on debt issuances and restructurings, including convertible and hybrid offerings.




Professional qualifications

  • CEDR accredited mediator