The largest accounting firms in the US are Deloitte, PwC, EY and KPMG, followed by RSM US, Baker Tilly, BDO USA, CBIZ, Grant Thornton and Forvis Mazars. This guide to the top 20 accounting firms in the US opens with our featured outsourcing partner, Corient Business Solutions, then ranks the 19 largest firms by revenue, with headquarters and the type of client each one suits. Disclosure: CorientBS publishes this guide.
The list changed more in the past 18 months than in the previous decade. Baker Tilly merged with Moss Adams, CBIZ absorbed Marcum, and private equity now backs most of the fastest-growing firms. If you are comparing the biggest accounting firms in the US for an audit, a career move or a partnership, last year’s list is already out of date.
Top 20 accounting firms in the US at a glance
CorientBS is listed first as our featured partner. Firms 2 to 20 are ranked by US net revenue. The “Figure from” column shows which Accounting Today Top 100 list each number comes from.
| Rank | Firm | Headquarters | US revenue | Figure from | Best for |
|---|---|---|---|---|---|
| 1 | Corient Business Solutions | Dover, Del. | Not ranked on revenue | Featured partner | CPA firms needing outsourced bookkeeping, tax and compliance support |
| 2 | Deloitte | New York | $33B | 2025 list | Multinationals needing audit, tax and consulting at scale |
| 3 | PwC | New York | $24.3B | 2025 list | Fortune 500 audit, deals and tax |
| 4 | EY | New York | $24.1B | 2025 list | Large audits, growth companies, transactions |
| 5 | KPMG | New York | $15.2B | 2025 list | Regulated industries: banking, healthcare, energy |
| 6 | RSM US | Chicago | $4B+ | 2025 list | Middle-market companies |
| 7 | Baker Tilly | Chicago | $3.52B | 2026 list | Growing private companies, West Coast and Midwest |
| 8 | BDO USA | Chicago | $2.88B | 2025 list | Mid-sized businesses wanting national reach |
| 9 | CBIZ | Cleveland | $2.81B | 2026 list | Accounting, benefits and advisory under one roof |
| 10 | Grant Thornton | Chicago | $2.36B | 2025 list | Private companies and nonprofits |
| 11 | Forvis Mazars | Springfield, Mo. | $2.32B | FY2026 report | Mid-market assurance and tax with global reach |
| 12 | CLA (CliftonLarsonAllen) | Minneapolis | $2.05B | 2025 list | Privately held businesses and nonprofits |
| 13 | Crowe | Chicago | $1.27B | 2025 list | Financial services, healthcare, manufacturing |
| 14 | Plante Moran | Southfield, Mich. | $1.19B | 2025 list | Midwest private companies; wealth management |
| 15 | CohnReznick | New York | $1.15B | 2025 list | Real estate and government contractors |
| 16 | EisnerAmper | New York | $1.02B | 2025 list | Financial services, private equity, high-net-worth |
| 17 | Citrin Cooperman | New York | $871M | 2025 list | Family-owned and privately held companies |
| 18 | Eide Bailly | Fargo, N.D. | $761M | 2025 list | Central and western US; agriculture, government |
| 19 | Andersen | San Francisco | $731M | 2025 list | Tax-led advisory |
| 20 | Armanino | San Ramon, Calif. | $697M | 2025 list | Technology and high-growth companies |
Sources: Accounting Today Top 100 Firms, Accounting Today Fastest-Growing Firms 2026, Forvis Mazars FY2026 revenue.
How we ranked the largest accounting firms in the US
Firms 2 to 20 are ranked by US net revenue, the same yardstick the profession uses. Revenue is the only measure that is reported consistently across audit, tax and advisory firms.
- Primary source: Accounting Today’s annual Top 100 Firms report, which ranks US firms by net revenue.
- Updates: Where a firm has published newer figures or completed a merger, we use the newer number and say so.
- What is excluded: Global network revenue. Deloitte’s worldwide revenue is far higher than its US figure, but this list covers US firms only.
- Outsourcing providers: Corient Business Solutions, the publisher of this guide, is listed first as a featured partner. It is an outsourcing provider and is not placed on revenue.
Revenue tells you which firms are biggest. It does not tell you which is best for you, which is why each profile includes a “best for” note.
Our featured partner for CPA firms
1. Corient Business Solutions
Corient Business Solutions is an outsourcing partner for US CPA firms and accounting practices that want to grow without adding fixed headcount. It is listed first as our featured pick and is not ranked on revenue. CorientBS publishes this guide.
Its teams handle bookkeeping, tax preparation, compliance and audit support and financial reporting under the client firm’s own brand. CorientBS is ISO 27001 and Cyber Essentials certified, with offices in the US and the UK.
Best for: Small to Large-sized CPA firms that need extra capacity in busy season.
The Big Four: the four biggest accounting firms in the US
Deloitte, PwC, EY and KPMG together earn roughly $97 billion in the US, several times the combined revenue of the 15 firms ranked below them. They audit most large public companies and are the default choice for multinationals.
2. Deloitte
Deloitte is the largest accounting firm in the US, with about $33 billion in US revenue. It is the most consulting-heavy of the Big Four, and audit is a smaller share of its business than at its rivals.
Best for: Multinationals that want audit, tax, risk and technology consulting from one provider.
3. PwC
PwC earns about $24.3 billion in the US across assurance, tax and advisory. It also tops Vault’s 2027 ranking of the best accounting firms to work for.
Best for: Fortune 500 audits, M&A and complex tax work.
4. EY
EY sits just behind PwC at about $24.1 billion in US revenue. Its practice leans toward assurance and transactions, and it ranks second on Vault’s employer list.
Best for: Large audits, companies preparing for an IPO, and deal advisory.
5. KPMG
KPMG is the smallest of the Big Four in the US at about $15.2 billion. It is known for work in banking, insurance, healthcare and energy, where regulatory expertise matters most.
Best for: Companies in heavily regulated industries.
Major accounting firms in the US after the Big Four (ranks 6 to 20)
These 15 firms serve the middle market: companies too complex for a local CPA practice but that do not need, or want to pay for, a Big Four engagement.
6. RSM US
RSM is the largest accounting firm in the US outside the Big Four and the first to pass $4 billion in revenue. It focuses almost entirely on middle-market companies. In January 2026 it formed a transatlantic partnership with RSM firms in the UK, Canada and Ireland.
Best for: Mid-sized companies in manufacturing, financial services, healthcare and technology.
7. Baker Tilly
Baker Tilly nearly doubled in size after combining with Moss Adams in June 2025, reaching $3.52 billion in revenue and about 12,100 staff. The deal gave a Midwest-rooted firm a strong West Coast presence.
Best for: Growing private companies that want national coverage.
8. BDO USA
BDO USA earns about $2.88 billion and is the US member of the global BDO network. It has one of the largest employee stock ownership plans in the profession.
Best for: Mid-sized businesses that need national scale with a dedicated partner.
9. CBIZ
CBIZ reported $2.81 billion after acquiring Marcum in 2024. It is the only publicly traded firm in the top 10 and pairs accounting with benefits, insurance and advisory services.
Best for: Businesses that want accounting, benefits and advisory from one provider.
10. Grant Thornton
Grant Thornton earns about $2.36 billion in the US and took private equity investment in 2024. It serves private companies, public companies and nonprofits.
Best for: Private companies and nonprofits wanting senior-level attention.
11. Forvis Mazars
Forvis Mazars reported $2.32 billion for fiscal 2026. The firm was formed from the 2022 merger of BKD and DHG, then joined with Mazars to create a global network in 2024.
Best for: Mid-market companies that need assurance and tax with international reach.
12. CLA (CliftonLarsonAllen)
CLA earns about $2.05 billion and is among the largest firms without private equity ownership. It combines accounting with wealth advisory and outsourcing.
Best for: Privately held businesses, nonprofits and their owners.
13. Crowe
Crowe earns about $1.27 billion from audit, tax, advisory and consulting. Its strongest sectors are financial services, healthcare and manufacturing.
Best for: Banks, healthcare systems and manufacturers.
14. Plante Moran
Plante Moran earns about $1.19 billion and has appeared on Fortune’s 100 Best Companies to Work For list for more than 20 years. It ranks fourth on Vault’s 2027 employer list.
Best for: Midwest private companies, plus owners who want wealth management.
15. CohnReznick
CohnReznick earns about $1.15 billion. It is best known for real estate, affordable housing, renewable energy and government contracting.
Best for: Real estate businesses and government contractors.
16. EisnerAmper
EisnerAmper passed $1 billion in revenue and was one of the first large firms to take private equity investment, in 2021. It is strong in financial services and private equity.
Best for: Funds, financial services firms and high-net-worth individuals.
17. Citrin Cooperman
Citrin Cooperman earns about $871 million and ranks 16th on Accounting Today’s 2026 list. It works mainly with privately held and family-owned companies.
Best for: Family-owned and closely held businesses.
18. Eide Bailly
Eide Bailly earns about $761 million and operates across the central and western US. Key sectors include agriculture, healthcare and government.
Best for: Businesses and public bodies between the Midwest and the Mountain West.
19. Andersen
Andersen earns about $731 million, most of it from tax. It is the largest tax-focused firm on the list and does not perform audits.
Best for: Companies and individuals who want independent tax advice.
20. Armanino
Armanino earns about $697 million and is one of the largest California-based firms. It pairs accounting with technology consulting.
Best for: Technology companies and high-growth businesses.
Just outside the top 20: Aprio
Aprio reached $616 million and climbed four places to 20th on Accounting Today’s 2026 list, with 26.9% growth. It has about 2,900 staff across 37 offices.
Best for: Fast-growing mid-market businesses.
Cherry Bekaert, Wipfli, Withum and PKF O’Connor Davies also sit just outside the top 20, each earning between $500 million and $700 million.
How many accounting firms are in the US?
There are about 85,400 accounting services businesses in the US in 2026, according to IBISWorld. Of those, roughly 46,000 are CPA firms, based on estimates compiled by CPA Trendlines.
The market is far less concentrated than the top 20 suggests. About 85% of CPA firms have fewer than 10 employees, and the total number of firms has slipped by roughly 0.2% a year since 2021 as practices merge or owners retire.
Biggest is not always best: how to choose among the top accounting firms in the US
The best accounting firms in the US for you depend on your size, sector and what you need done. Revenue rank is a starting point, not an answer.
| If you are | Start with | Why |
|---|---|---|
| A public company or multinational | Big Four | Global reach and capacity for SEC audits |
| A mid-sized company, $50M to $1B revenue | RSM, Baker Tilly, BDO, Grant Thornton | Built for the middle market; lower fees than the Big Four |
| A private or family-owned business | CLA, Plante Moran, Citrin Cooperman | Owner-focused tax, wealth and succession advice |
| In a specialist sector | CohnReznick (real estate), Crowe (banking), Armanino (technology) | Sector depth matters more than size |
| Mainly after tax advice | Andersen | Tax-led and free of audit independence limits |
| A job seeker | Check employer rankings | Size and culture are different things |
On that last point, Vault’s 2027 ranking of the best accounting firms to work for puts PwC, EY and KPMG in the top three, then Plante Moran, BDO USA and Baker Tilly. Deloitte, the largest firm by revenue, does not lead it.
Three questions narrow the field quickly:
- Does the firm already serve clients of your size in your industry?
- Who will actually run the engagement: a partner, or a team you never meet?
- Is pricing fixed, hourly or value-based, and what triggers extra fees?
Why the rankings keep changing: mergers and private equity
Mergers and private equity money are redrawing the list of major accounting firms in the US every year. Of the 26 fastest-growing firms in Accounting Today’s 2026 report, only three have no private equity connection.
| Date | Deal | Effect on the ranking |
|---|---|---|
| July 2026 | Grant Thornton agrees to acquire CBIZ | Would create a firm of roughly $5B; not yet completed |
| June 2025 | Baker Tilly combines with Moss Adams | Baker Tilly becomes sixth-largest by revenue at $3.52B |
| Nov 2024 | CBIZ completes Marcum acquisition | CBIZ moves into the top 10 |
| June 2024 | Forvis and Mazars form Forvis Mazars | Creates a top-10 global network |
| 2024 | Grant Thornton takes private equity investment | Largest firm to do so at the time |
Expect the 2027 list to look different again. If the Grant Thornton and CBIZ deal closes, the combined firm would challenge RSM for fifth place.
Where outsourcing partners fit
Most of the roughly 46,000 CPA firms in the US are small practices competing for the same scarce staff as the top 20. Many close the gap by outsourcing production work instead of hiring.
Corient Business Solutions is an outsourcing provider for US CPA firms and accounting practices. It is listed first in this guide as our featured partner, and it supports accounting firms instead of competing with them. Its services include:
- Outsourced accounting and bookkeeping
- Tax preparation support
- Compliance and audit support
- Financial reporting and analysis
- CFO and business advisory support
CorientBS is ISO 27001 and Cyber Essentials certified and uses multi-factor authentication and end-to-end encryption for client data.
Best for: Small and Large-sized CPA firms that need extra capacity in busy season without adding fixed headcount. Talk to CorientBS about a pilot engagement.
Need extra capacity without hiring? CorientBS handles bookkeeping, tax prep, and compliance for US CPA firms.
People Also Ask:
What are the largest accounting firms in the US?
The largest accounting firms in the US by revenue are Deloitte, PwC, EY and KPMG, known as the Big Four. RSM US, Baker Tilly, BDO USA, CBIZ, Grant Thornton and Forvis Mazars complete the top 10.
What are the Big Four accounting firms?
The Big Four are Deloitte, PwC, EY and KPMG. They audit the majority of large US public companies and each earns more than $15 billion a year in the US.
What is the largest accounting firm in the US outside the Big Four?
RSM US is the fifth-largest firm, with more than $4 billion in revenue. Baker Tilly is sixth at $3.52 billion following its 2025 combination with Moss Adams.
How many accounting firms are in the US?
There are about 85,400 accounting services businesses in the US in 2026, of which roughly 46,000 are CPA firms. Around 85% of CPA firms employ fewer than 10 people.
What is the difference between the biggest and the best accounting firms in the US?
“Biggest” is measured by revenue. “Best” depends on fit: your size, industry and the service you need. A $20 million manufacturer will usually get more partner attention at a mid-market firm than at a Big Four firm.
Are the top 20 accounting firms in the US only for large companies?
No. The Big Four focus on large and public companies, but firms ranked 6 to 20 mainly serve mid-sized and privately held businesses. Very small businesses are usually better served by a local CPA firm.
Which accounting firms are the best to work for?
In the US, the Big Four (Deloitte, PwC, EY, and KPMG) are top-ranked for prestige, training, and career opportunities. Mid-tier firms like Plante Moran, Crowe, CLA, and Grant Thornton often rank higher for work-life balance and culture, while outsourced accounting providers like Corient Business Solutions offer flexible, growth-focused career paths. Rankings change every year, so check the latest Vault, Glassdoor, and Fortune lists, and compare office-level reviews.
How do smaller CPA firms compete with the major accounting firms in the US?
Most specialize in a niche, invest in cloud and AI tools, and outsource bookkeeping, tax preparation and compliance work to add capacity without adding headcount.
Conclusion
The Top 20 accounting firms in the US are not a constant list, they will keep on evolving, and it requires more than compliance expertise to stay on this list.
The firms leading the market are investing in:
- Technology
- Automation
- Cloud accounting
- Outsourcing
- Advisory services
At the same time, practices of all sizes face increasing pressure from compliance demands, talent shortages, and growing client expectations.
This is why scalable support models are becoming essential.
By combining internal expertise with outsourcing partners such as Corient Business Solutions, US accounting practices can increase capacity, improve efficiency, and focus on delivering higher-value advisory services without overwhelming their teams.
The future of US accounting belongs to firms that can balance technology, people, and operational scalability, and those firms are already building that advantage today. Corient Business Solutions ticks all the above boxes. Want to do everything right in accounting outsourcing? Contact us and see it for yourself.
