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Siobhan Duncan

Siobhan joined Temple Tax Chambers following the successful completion of her pupillage in April 2023.


Siobhan accepts instructions from solicitors and accountants across Chambers broad range of expertise, advising on both direct and indirect taxes.


Practice overview




  • Assisting in a case concerning penalties brought under the Taxes Management Act 1970 (ongoing)
  • Instructed as junior in an appeal against discovery assessments (ongoing)
  • Instructed as junior in a transactions in securities appeal (ongoing)
  • VAT penalties appeal under Schedule 24 of the Finance Act 2007 (ongoing)




  • Capital gains tax (including advice concerning disposals/transfers of agricultural land, and residential and commercial property)
  • Inheritance tax
  • Landfill tax
  • Qualification for an employee shareholder scheme
  • Residence and domicile advice (including potential UK tax liabilities arising)
  • Stamp duty
  • Stamp Duty Land Tax
  • Taxation advice concerning surrendered foreign life insurance policies
  • VAT (notably, the VAT implications of cross-border electricity trading)


Drafting and registrations


  • Registrations of overseas entities
  • Trusts drafting
  • Trust registrations



Education, Professional Memberships and Appointments

  • LLM (Master of Laws), New York University School of Law (2020)
  • Bar Professional Training Course, City University London (2017)
  • LLM (Master of Laws), University College London (2015)
  • LLB (Hons) Law with French Law, with First Class Honours, University of Westminster (2014)
  • Certificat de Droit Français, Montesquieu University – Bordeaux IV, France, (2013)
  • Member of the Revenue Bar Association

Recent Cases


Osmond and another v Revenue and Customs Commissioners [2024] UKFTT 378 (TC)


Mark Campbell v HM Revenue and Customs [2023] UKUT 00265 (TCC)


Kenan Altunis and HMRC [2023] UKFTT 719 (TC)



Siobhan is a contributing author for LexisPSL and her recent contributions are as follows:


Intellectual Property (IP)


Other Experience


Siobhan brings with her a diverse legal background, primarily in the commercial sector.  Before coming to the Bar, Siobhan worked at prestigious institutions including Imperial College London as a lead legal contracts negotiator and the Office of the New York State Attorney General (Antitrust Bureau) where she assisted in the high-profile merger case State of New York et al v Deutsche Telekom AG et al.

Additional Information


Awards and Scholarships


  • Pupil Award, Inner Temple (2021)
  • Graduate Merit Scholarship, Alpha Kappa Alpha Educational Advancement Foundation (2019)
  • Profumo Scholarship, Inner Temple (2015)
  • Major Exhibition Award, Inner Temple (2015)
  • Duke of Edinburgh Entrance Award, Inner Temple (2015)
  • City Law School BPTC Award, City University London (2015)
  • 21st Century Law School Scholarship (sponsored by LexisNexis UK), University of Westminster (2014)




  • French (full professional proficiency)


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Our Members

Alun James
Michael Sherry
Jonathan S. Schwarz
Tim Brown
Scott Redpath
Michael Collins
Philip Ridgway
Stephen Arthur
Michael Quinlan
Keith M Gordon
Ximena Montes Manzano
Lyndsey Frawley
David Pett
Michael Avient
Denis Edwards
Siobhan Duncan

Our Clerks

Lucy Campbell
Senior Clerk
Cindy Green
Kaylin O'Rourke
Tracey Oliver
Chambers' Administrator

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