Gemma Stack

Overview

Gemma Stack is a Principal in Ryan’s Employment Tax practice, based in the Firm’s London office. She advises businesses on employment tax, reward, and workforce compliance matters across the United Kingdom and international environments, helping organizations navigate regulatory complexity with clear, commercially grounded guidance. Gemma works closely with HR, finance, payroll, legal, and mobility teams to design practical, technology-enabled solutions that support sustainable workforce models and align with broader operational and strategic objectives.

With extensive experience across global advisory environments, Gemma brings a pragmatic and people-focused approach to employment tax consulting. She advises on year-end reporting, HMRC disputes and enquiries, National Living Wage compliance, employment status, reward structures, mobility, business travel, and regulatory reporting. Her background includes leading digital employment tax initiatives and supporting organizations through evolving workforce and cross-border employment challenges. Known for building collaborative, high-performing teams, Gemma is passionate about mentoring talent and fostering environments where people can perform at their best while delivering measurable outcomes for clients.

Education and Qualifications

Institute of Chartered Accountants in England and Wales (ICAEW), Accounting Exams

Bachelor of Science (Honors), Economics, London School of Economics & Political Science (LSE)

Experience and Achievements

Principal, Employment Tax, Ryan, London office

• Advises clients on employment tax, reward and workforce compliance matters, helping them manage risk and cost while enabling strategic workforce decisions

• Leads and supports client engagements across payroll, global mobility, reward and people tax issues, delivering practical and commercially focused outcomes - Partners with cross-functional teams to deliver consistent, high quality client service on complex cross-border matters

Reward Tax Partner, Big Four Firm, United Kingdom

• Provided senior leadership within the people and reward tax practice

• Led digital employment tax and reward initiatives focused on scalable advisory solutions

• Advised clients on domestic employment tax matters, internationally mobile employees, cross-border work, and evolving reward models

• Built and led multidisciplinary advisory teams with a focus on coaching and capability development