The landscape has shifted noticeably in recent years. The FRC published its first AI-in-audit guidance in June 2025, formalising how firms can use machine learning and generative AI in audit workflows. Meanwhile, 44% of the UK's top 100 accountancy firms engaged in M&A activity in 2025, reshaping the mid-tier market at pace.
This article ranks the top 10 UK accountancy firms for 2025, covering what each firm does best, who it serves, and how to decide which one fits your business.
Key Takeaways
- PwC leads the UK market by revenue at £4.27bn (FY2025), with Deloitte and EY close behind
- The Big Four dominate large-company audit — earning 98% of FTSE 350 audit fees in 2023
- Mid-tier firms are growing fast — Moore UK posted 28.3% revenue growth in FY2025, outpacing many Big Four rivals
- Firm size does not equal best fit — SMEs and mid-market companies often get better value and service from BDO, RSM, or Azets
- Selection criteria matter more than brand — match by sector, software compatibility, geography, and fee transparency
The UK Accountancy Industry in 2025: A Quick Overview
UK accountancy firms cover a broad remit: audit and assurance, tax compliance, financial reporting, payroll, corporate finance, and advisory.
Every UK company with a registered entity must comply with HMRC filing requirements, Companies House obligations, and reporting standards under UK GAAP or IFRS — creating consistent demand across all business sizes.
Three shifts are reshaping how firms compete this year:
- AI integration in audit — the FRC's June 2025 guidance clarified documentation standards for AI tools, accelerating adoption across the profession
- Mid-tier consolidation: nearly half of the top 100 firms pursued mergers and acquisitions (M&A), creating larger regional players with national reach
- ESG advisory growth, with non-financial reporting now a meaningful revenue driver for the largest firms
The firms below are ranked by verified UK annual revenue from official filings and trade rankings (Accountancy Age Top 50+50 and Accountancy Today Top 30), with additional consideration given to service breadth, geographic reach, and client profile alignment.
Top 10 Accountancy Firms in the UK 2025
1. PwC (PricewaterhouseCoopers)
PwC is the UK's largest accountancy firm by statutory revenue, operating from 19 UK offices. Its services span audit and assurance, tax advisory, consulting, deals and transactions, and risk — with a client base that includes a significant proportion of the FTSE 350 and Global Fortune 500.
For FY ended 30 June 2025, PwC reported UK statutory revenue of £4.27bn. Its global network covers 136 countries. Proprietary audit tools — including Halo (large-volume data testing) and Aura — underpin its audit quality proposition.
| Category | Details |
|---|---|
| Key Services | Audit & Assurance, Tax Advisory, Consulting, Deals & Transactions, Risk |
| Best Suited For | Large multinationals, FTSE-listed companies, public sector bodies |
| UK Footprint | 19 offices, global network of 364,782 people |
2. Deloitte
Deloitte is the second-largest UK firm by revenue, with 26,000 people and 1,458 partners across the UK. It reported revenue of £5.68bn for FY ended May 2025 — though this figure reflects its broader UK operations — down 1% year-on-year.
Those headline numbers sit on a notable technology foundation: Deloitte's Omnia digital audit platform incorporates AI-enabled capabilities for audits of varying scale and complexity. The firm has made notable investments in sustainability advisory and digital transformation, with particular strength in financial services and private equity.
| Category | Details |
|---|---|
| Key Services | Audit, Financial Advisory, Risk Consulting, Tax, Digital Transformation |
| Best Suited For | Enterprise clients, financial services, private equity, public sector |
| UK Footprint | 24,498 employees, 1,458 partners, new offices in Bristol and Aberdeen (FY2025) |
3. EY (Ernst & Young)
EY reported UK fee income of £3.78bn for FY ended June 2025, representing 2% growth year-on-year. With more than 20,000 employees, 930 partners, and 22 UK offices, EY ranks third among the Big Four by UK revenue.
The firm's EY.ai platform and blockchain practice reflect its technology-first positioning. EY has particular depth in financial services, energy, and consumer products, and its ESG advisory work — including the EY Four Futures sustainability framework — is one of the most developed among the Big Four.
| Category | Details |
|---|---|
| Key Services | Audit & Assurance, Tax Compliance, Strategy & Transactions, Consulting |
| Best Suited For | Financial services firms, tech companies, mid-to-large enterprises seeking ESG advisory |
| UK Footprint | 22 offices, 20,000+ employees, 930 partners |
4. KPMG
KPMG rounds out the Big Four with UK revenue of £2.99bn for the year ended September 2024, up marginally from £2.96bn the prior year. Audit gross revenue stood at £919m. The firm employs an average of 16,673 UK staff.
KPMG's Clara AI chat tool — built on Microsoft Azure OpenAI and launched for all UK auditors in 2024 — is a tangible example of its technology investment. The firm's alliances with Microsoft, Oracle, and SAP make it a natural fit for organisations running enterprise-grade compliance workflows.
| Category | Details |
|---|---|
| Key Services | Audit, Tax Strategy, Risk Management, Consulting, Regulatory Compliance |
| Best Suited For | Multinationals, regulated industries (financial services, healthcare), public sector |
| UK Footprint | Multiple offices, ~16,673 employees |
5. BDO
BDO crossed the £1bn revenue threshold in FY2024 and posted revenues of £1.005bn for FY ended July 2025, maintaining that milestone in a challenging market. With 8,000 people across 18 UK locations and 501 partners, it is the largest firm outside the Big Four.
BDO audits more UK listed entities than any other firm outside the Big Four. Its client model blends large-network resources with direct partner access — a combination mid-market companies and family enterprises often find more responsive than their larger counterparts.
| Category | Details |
|---|---|
| Key Services | Audit, Tax (Corporate & VAT), Advisory, Business Outsourcing, Payroll |
| Best Suited For | Mid-market companies, family-owned businesses, entrepreneurial ventures |
| UK Footprint | 18 offices, 8,000 people, 501 partners |
6. Grant Thornton
Grant Thornton posted revenue of £787m in 2025, with 4% top-line growth and underlying operating profit up 30% to £189m. The firm employs over 5,000 people across 23 UK offices, with 257 equity partners.
The sector reach behind those numbers is notable: the firm advises 61% of FTSE 100 companies and holds a 35% share of NHS audit work.
Its forensic practice is ranked Band 1 by Chambers and Partners, covering dispute resolution, investigations, and contentious valuations — making it a strong choice for mid-market businesses and public interest entities that need both audit depth and specialist advisory.
| Category | Details |
|---|---|
| Key Services | Audit, Tax Advisory, CFO Services, ESG Advisory, Forensic Investigations |
| Best Suited For | Mid-market companies, fast-growth businesses, public interest entities, not-for-profits |
| UK Footprint | 23 offices, 5,000+ employees, 257 equity partners |
7. RSM UK
RSM UK generated nearly £600m in revenue for FY2024/25, a near 10% increase, with consulting (£223m), tax (£183m), and audit (£188m) contributing roughly evenly. The firm has 5,420 partners and staff across 29 UK locations.
RSM's geographic distribution — 29 offices across England, Scotland, Wales, and Northern Ireland — gives it one of the strongest regional footprints outside the Big Four. Proprietary tools extend its value well beyond core audit and tax:
- Pay Manager — cloud payroll platform
- People Manager — HR administration
- InTime — pay-and-bill solution for recruitment businesses
| Category | Details |
|---|---|
| Key Services | Audit, Tax (Corporate, VAT, Indirect), Risk Advisory, Payroll, International Services |
| Best Suited For | Family businesses, consumer-sector companies, mid-market firms needing strong regional coverage |
| UK Footprint | 29 locations, 5,420 partners and staff |
8. Forvis Mazars
Forvis Mazars (rebranded from Mazars following its merger with Forvis in 2024) reported UK revenue of £391.9m for FY ended August 2025, up 8.1%. UK headcount reached 3,542, with 170 partners across 14 UK offices.
The firm's cross-border credentials are its strongest differentiator: Forvis Mazars operates as an integrated partnership across more than 100 countries and territories, making it particularly well-suited to mid-sized businesses with international footprints. Its sector depth spans real estate, retail, energy, and media.
| Category | Details |
|---|---|
| Key Services | Audit, Tax Advisory, Financial Advisory, Payroll, Outsourcing |
| Best Suited For | Mid-sized international businesses, real estate, retail, and energy sector clients |
| UK Footprint | 14 offices, 3,542 people, 170 partners |
9. Moore UK
Moore UK delivered standout growth in FY2025 — UK fee income of £323m, representing 28.3% year-on-year growth, the strongest rate among the firms in this list. The firm has 281 UK partners and approximately 2,985 employees across 38 offices.
Moore UK firms are Xero Platinum Partners and carry deep expertise in QuickBooks and FreeAgent, making them a practical choice for SMEs that already use cloud accounting platforms. As part of the global Moore network (founded 1907, now spanning over 100 countries), it combines international reach with local service delivery.
| Category | Details |
|---|---|
| Key Services | Bookkeeping, Advisory, Payroll (PAYE, Pensions, P60), Tax (VAT, Returns), Audit |
| Best Suited For | SMEs, owner-managed businesses, growing enterprises seeking scalable support |
| UK Footprint | 38 offices, ~2,985 employees, 281 partners |
10. Azets
Azets rounds out the Top 10 with UK fee income of £404m for FY ended June 2025 (including Blick Rothenberg), up 9.9% year-on-year, according to Accountancy Age. The firm has 351 UK partners, over 3,800 people, and 60 UK office locations — the widest geographic spread of any firm on this list.
Azets serves over 80,000 UK clients, with a deliberate focus on SMEs, early-stage businesses, and owner-managed enterprises. For businesses that want regional familiarity without sacrificing the backing of a substantial network, the sheer depth of local office coverage sets Azets apart from most mid-tier alternatives.
| Category | Details |
|---|---|
| Key Services | Online Accounting, Tax, Audit, Payroll Processing, Financial Analysis |
| Best Suited For | SMEs, local businesses, early-stage growth companies, owner-managed businesses |
| UK Footprint | 60 offices, 3,800+ people, 351 partners |
How We Chose the Best Accountancy Firms for This List
Each firm on this list was evaluated using consistent, verifiable data — not reputation alone.
Primary ranking factor: Verified UK annual revenue from official company filings, the Accountancy Age Top 50+50 2025, and the Accountancy Today Top 30 2025. Where statutory revenue and trade-reported fee income differed, we noted the distinction rather than conflating the figures.
A common mistake is selecting a firm based on name recognition alone. A Big Four firm can be overkill for an SME — and costly — while a boutique regional firm may lack the capacity to support a multinational's cross-border compliance needs.
Secondary evaluation criteria:
| Criterion | Why It Matters |
|---|---|
| Service breadth and sector specialisation | Sector expertise prevents costly regulatory missteps |
| UK geographic presence | Regional offices mean faster, on-the-ground support |
| Technology and software integration | Cloud platform compatibility reduces friction and error |
| Client profile alignment | SME vs. enterprise needs differ significantly in complexity and cost |
| Regulatory standing | FRC registration, ICAEW, and ACCA accreditation confirm professional standards |
We excluded outsourced and virtual-only accounting providers to maintain like-for-like comparability with firms offering a full UK audit, tax, and advisory practice.
Conclusion
The UK accountancy market in 2025 is well-resourced and clearly differentiated. The Big Four — PwC, Deloitte, EY, and KPMG — continue to dominate large-company audit and advisory, collectively earning 98% of FTSE 350 audit fees. But mid-tier firms like BDO, Grant Thornton, RSM, and Azets are capturing meaningful market share, particularly in the owner-managed and mid-market segments.
The right firm is the one that fits your operational complexity, not necessarily the largest one. Before finalising any engagement, assess three things:
- Scalability: will the firm's capacity and sector expertise hold up as your business grows?
- Fee transparency: is pricing fixed, itemised, and proportionate to your size — or vague until the invoice arrives?
- Communication: does the team flag compliance deadlines proactively, or do you end up chasing them?
A short consultation and two or three client references before signing can prevent months of unnecessary friction.
For UK businesses with operations in India, domestic accountancy support covers only half the picture. VJM Global — with 30+ years of experience and more than 250 UK businesses served — provides accounting, tax compliance, GST advisory, audit, payroll, and business setup support specifically for UK companies operating in the Indian market.
From FDI policy analysis and entity registration through to transfer pricing documentation and expatriate tax planning, VJM Global manages Indian regulatory and financial obligations directly. Contact VJM Global at info@vjmglobal.com to discuss your India-market accounting needs.
Frequently Asked Questions
What are the top 10 accounting firms in the UK?
The top 10 UK accountancy firms by 2025 revenue are: PwC, Deloitte, EY, KPMG, BDO, Grant Thornton, RSM UK, Forvis Mazars, Moore UK, and Azets. PwC holds the top spot by UK statutory revenue at £4.27bn for FY2025.
Who are the Big 4 in the UK?
The Big Four are PwC, Deloitte, EY, and KPMG. These four firms dominate the UK market by revenue, global reach, and client scope — earning 98% of FTSE 350 audit fees in 2023 and serving the majority of large multinational and listed-company clients.
What is the largest accounting firm in the UK?
PwC (PricewaterhouseCoopers) is the largest UK accountancy firm by statutory revenue, reporting £4.27bn for the financial year ended June 2025, with 19 UK offices and a global network covering 136 countries.
What is the difference between a Big 4 firm and a mid-tier accountancy firm in the UK?
Big Four firms (PwC, Deloitte, EY, KPMG) serve large multinationals, listed companies, and complex cross-border clients. Mid-tier firms like BDO, Grant Thornton, and RSM focus on mid-market and owner-managed businesses, typically offering more accessible pricing, direct partner relationships, and stronger sector specialisation.
How do I choose the right accountancy firm for my business in the UK?
Start by matching the firm's typical client profile to your business size and complexity. Then verify sector experience, software compatibility, professional accreditations (ICAEW, ACCA, FRC registration), and whether fee structures are transparent and scalable.
Do UK accountancy firms provide support for businesses with international operations?
Most top UK firms — particularly the Big Four and mid-tier firms with global networks like Forvis Mazars, Moore UK, and RSM — offer international advisory. However, businesses operating in specific markets like India often benefit from engaging a local specialist alongside their UK firm, given the complexity of local tax law, FDI regulations, and compliance requirements.
