Based in London, Mr Lappin brings more than 25 years of experience in tax advisory and commercial leadership, including senior roles at EY, where he led go-to-market and sales strategies for the tax division. During his time there he worked across a global client base, significantly increasing client engagement and driving substantial revenue growth.

At AAB, Mr Lappin will lead the continued evolution of the firm’s tax proposition, focused on strategic segmentation, sector alignment and performance-led delivery. His appointment marks a pivotal moment for AAB’s tax discipline, aligning with the firm’s continued expansion and investment in serving complex client needs across multiple service lines.

The strength of AAB’s tax team has been recognised nationally, with the firm recently shortlisted for ‘Tax Team of the Year’ at the 2025 Accounting Excellence Awards.

Mr Lappin said: “We are at a pivotal point in the evolution of tax, both in terms of increasing complexity and accelerating change.

“The expectations of clients, regulators and our own people are shifting rapidly. Whether it’s navigating the impact of global tax reform, embracing technological transformation, or responding to new compliance and transparency demands, the tax landscape is fundamentally changing.

“What attracted me to AAB is the ability to address these challenges head-on, with a team that blends technical excellence with a people-first mindset. AAB’s breadth of expertise, from corporate tax to innovation, indirect tax, customs and private client services, means we can support every type of client, from individuals to SMEs and multi-entity international businesses, under one roof. I’m excited to help our teams and our clients not just respond to these changes, but to capitalise on the opportunities they present.”

John Beevers, head of professional services at AAB, added: “We’re thrilled to welcome Mark to AAB at a time of both opportunity and transformation across our industry. His deep expertise and authentic leadership style are exactly what we need as we help clients navigate today’s tax complexities, from reform and regulation to technological disruption.

“Mark’s collaborative approach will be instrumental in working with other business units across AAB, allowing us to offer clients a truly seamless, joined-up service that combines the best of tax, audit, advisory and beyond. He will play a critical role in shaping the next phase of our journey, ensuring that we remain bold, ambitious and focused on delivering long-term value for clients.”

Mr Lappin’s appointment follows a series of senior hires in AAB’s London office, which has become a key strategic hub for the group’s growth. While based in the capital, Mr Lappin will lead with a location-agnostic approach, ensuring national consistency while continuing to serve the firm’s clients across the UK and internationally.