The Largest Accountancy Firms in the UK (2025 Edition) When it comes to targeting accountants, understanding the landscape of the largest accountancy firms in the UK is crucial for any business looking to expand its B2B reach. Size matters in accountancy—not only because larger firms offer a wider scope of services and carry considerable reputational weight, but also due to their extensive employee base, which provides a rich network for marketing and sales efforts. In 2025, the UK accountancy sector is undergoing rapid change. Mergers and acquisitions (M&A), digitalisation, and audit reforms are reshaping how firms operate and engage with clients. For businesses aiming to connect with professionals in this field, targeting the largest accountancy firms presents an excellent opportunity to access decision-makers and influencers at scale. This blog draws on publicly available data from 2024–2025 to present a definitive list of the largest accountancy firms in the UK. Whether you are...