O’Melveny Worldwide

Jan Birtwell has extensive experience advising on the UK and international tax aspects of corporate finance/M&A transactions and on the tax structuring of investment funds, particularly those focusing on private equity, infrastructure, clean tech and mezzanine/debt (including distressed debt situations). Jan also advises on the tax aspects of downstream (buyout/deal side) private equity/alternative investment businesses, including the corporate and financial restructuring of such businesses, secondary transactions and on the structuring of management incentive arrangements for the funds and their portfolio investments.

Jan is recognised as a leading practitioner in the field of Tax by Chambers and Partners’ UK and Global editions, drawing praise for her in-depth industry knowledge and “clear and concise communication.” The publications credited her collaborative approach as making her “tremendously easy to work with.” Jan also is the founder of the TransAtlantic Tax Group, an association of more than 100 tax practitioners at US law firms in London.

In addition to her busy tax practice, Jan is the managing partner of O’Melveny’s London office.

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  • Advising on fund and co-investment structures suitable for a spectrum of investor types based in various jurisdictions and reflecting different investment strategies and on the structures of underlying investments 
  • Advising a sovereign wealth fund on its investments into private equity and real estate funds raised by leading fund managers/houses in Europe and Asia and on related co-investment arrangements 
  • Advising private equity houses on leveraged buy-outs, secondary transactions and on sales of portfolio companies 
  • Advising on acquisitions of UK and European companies and businesses by US clients



  • Supreme Court of England and Wales


  • University of Bristol, LLB, with honors, 1983
  • College of Law (Guildford), Law Society Final Examinations Part II, 1984

Honors & Awards

  • Recognized by Chambers UK for Tax (2019-2020) and by Chambers Global and Chambers Europe for Tax (2020)

Professional Activities


  • IFA and Founding Member of the TransAtlantic Tax Group, a group of UK tax lawyers at US law firms in London