Iain was called to the Bar in 2006 and his practice focuses on contentious tax, commercial & chancery litigation, fraud and investigations.  He has litigated some of the leading cases on VAT fraud, injunctive relief and HMRC investigatory powers.

Iain is recommended in the Legal 500 and manages a wide variety of work for an international client base, ranging from HNWIs to PLCs and owner-managed businesses to trusts and funds.  He is often sought out by other legal and professional advisors for a second opinion and to help ‘unlock’ long-running or complex problems.

Before pupillage, Iain worked for HMRC Solicitor’s Office in both excise litigation and VAT litigation. He has acted as counsel both for and against HMRC in a variety of disputes in the Tax Tribunal, High Court and Court of Appeal.  He became a partner at JHA in 2021 and prior to that had been a tenant at a leading set of chambers and a dispute resolution partner at a City law firm.


Called to the Bar of England & Wales, March 2006


‘Iain MacWhannell – charming and forensically bright. He has fantastic judgment and instinctively knows the right decisions to make in complex, high value commercial litigation. As a former barrister, Iain’s tactics are at the heart of what he does and why he is so very much in demand. Revered for his knowledge and experience of FS, tax, civil fraud and injunctions work, he has a proven track record in heavy weight litigation.’ (Legal 500, 2020)

‘Iain MacWhannell is excellent. He has a keen eye for detail and is an excellent negotiator and litigator. Clients are in the safest of hands with Iain.’ (Legal 500, 2020)