Ten of the top audit firms in the world in 2023

In a world where credibility is key, businesses must ensure that their financial accounts are accurate, up to date, and in line with the latest regulatory requirements. And that means undergoing regular audits. 

To service this ever-growing need, the auditing industry is constantly growing. The global market for auditing services currently stands at well over $200 billion and is estimated to hit over $280 billion by 2026. 

While smaller accounting firms continue to do well serving the local community and smaller businesses, the market is dominated by global accounting behemoths. In this article, we’ll look at ten of the biggest.

But before we dive in, let’s answer an important question…

Are audit firms and accounting firms the same thing?

Generally speaking, the answer is yes. 

Although audit and accounting are different practices, they are closely related and share the same general goal: To ensure the accuracy and reliability of a business’s finances. 

For a clearer picture, let’s define what these two areas involve: 

• Accounting is the process of recording and summarising a business’s financial transactions. This can be done by an internal accounting department, or it can be outsourced to an accounting firm. 
• Auditing is the process of examining a business’s accounting records to ensure that they are accurate and compliant. This is always done by an independent firm and is often required by law.

Because these two areas are so closely related, many accounting firms also offer audit services — and vice versa. This is especially true of larger accounting firms, like the ones we’ve highlighted in this list. So, for the sake of clarity, we’ll use the terms “accounting firms” and “audit firms” interchangeably in this article. 

Now that we’ve cleared that up, let’s dive into the list! 

1. Deloitte

Revenue: $59.3 billion

Number of employees: 412,000

HQ: London, UK

Kicking off our list is Deloitte Touche Tohmatsu Limited, or Deloitte for short, which is widely known as the largest accounting firm in the world. Established in 1845, Deloitte is a professional services network with a truly global reach. Its headquarters are in London, UK, but it has over 700 offices across 150 countries worldwide. 

Deloitte is a true auditing juggernaut, bringing in over $11 billion from its audit and assurance function alone. Besides audit, it offers a range of consulting services focused on the following areas: 

• Legal advisory
• Managed services
• Tax services
• Business consulting services
• Financial advisory, including wealth management and investment management
• Risk advisory

Among strong competition, Deloitte has consistently ranked as the number one accounting and professional services firm. It’s also widely seen as one of the best places to launch a career in accounting, audit, tax, or legal. 

2. PwC

Revenue: $50.3 billion

Employees: 328,000

HQ: London, UK

PricewaterhouseCoopers, usually referred to as PwC, is the second-largest accounting firm in the world. In terms of its revenue, workforce, and global reach, it’s hot on the heels of Deloitte. PwC currently has 742 regional offices in 157 countries.

Despite trailing Deloitte on total revenue, PwC leads the way in terms of revenue derived from audit and assurance, raking in $18 billion from this function alone. Interestingly, PwC has the highest revenue per employee of the Big Four accounting firms, suggesting a very well-run organisation.

In addition to audit, PwC offers a full portfolio of services, including: 

• Legal services
• Advisory services
• Tax services
• Global consulting services, including management consulting
• Forensic intelligence and analytics

PwC is known as a forward-thinking firm, with a strong focus on sustainability, technology, and innovation.   

3. EY

Revenue: $45.4 billion

Employees: 365,000

HQ: London, UK

Ernst & Young Global Limited, or EY for short, is currently the third-biggest audit firm in the world. In 2022, it brought in almost a third ($14.4 billion) of its revenue via its audit and assurance services. And in employee headcount terms, it’s second only to Delotte. 

Founded in 1989 through the merger of two much older firms, Ernst & Young has since gone through a highly successful rebrand. Besides audit, its core offerings include: 

• Consulting services
• People and workforce
• Transactions and corporate finance
• Tax services
• Legal
• Managed services

Like many of the other firms on this list, Ernst & Young positions itself as a thought leader in areas such as technology, innovation, digital transformation, and sustainability. 

4. KPMG 

Revenue: $34.6 billion

Employees: 265,000

HQ: Amstelveen, Netherlands

Rounding off the Big Four accounting firms, KPMG is another giant in the audit world. In fact, it has traditionally been more audit-focused than its competitors, directing plenty of investment into its audit practice and technology. 

Besides audit and assurance, KPMG offers a range of services split across three core areas: 

• Tax and legal
• Advisory
• Private enterprise

With roots dating back to 1897, KPMG is the result of several mergers. It has since established itself as one of the largest businesses in the world, boasting a network of firms covering 145 countries. 

5. BDO Global

Revenue: $11.8 billion

Employees: 97,200

HQ: Zaventem, Belgium

The fifth-largest accounting firm in the world, BDO Global is the current leader among the so-called mid-tier accounting firms. But don’t be fooled by the term “mid-tier” - BDO is still a massive player in the audit world, with a whopping 1,800 offices spread across 164 countries. 

Given that the Big Four have a monopoly on enterprises and large organisations, BDO focuses on middle-market clients. Its services are tailored to the needs of mid-sized businesses and cover three core offerings: 

• Audit and assurance
• Tax 
• Advisory

BDO is also known for having an entrepreneurial culture, making it a great choice for clients looking for a more flexible, personalised, and fast-moving approach.

6. RSM

Revenue: $8 billion

Employees: 57,000

HQ: London, UK

RSM is a global network of accounting, finance, tax, and audit experts. They have 830 offices spread across 120 countries. While it might not be a household name like the Big Four firms, RSM is among the top accounting firms in the world, particularly in the US. Their services include:  

• Audit and assurance
• Consulting services
• Digital services
• Tax services
• Legal services and financial due diligence

RSM has a strong focus on technology-driven solutions, personalised services, and thought leadership within the accounting and audit space. In terms of revenue, RSM is among the fastest-growing accounting firms on this list. 

7. Grant Thornton International

Revenue: $7.2 billion

Employees: 68,000

HQ: London, UK

Another accounting firm with a global reach, Grant Thornton International is well known for offering high-quality professional services, innovative solutions, and a client-centric approach. They offer a broad range of services across three main areas: 

• Advisory
• Assurance (including audit) 
• Tax

Their audit offering includes audit quality monitoring, which ensures a consistently good service worldwide. They also apply their audit methodology via a set of proprietary software tools, known as the Voyager suite.

8. Baker Tilly International

Revenue: $4.6 billion

Employees: 39,000

HQ: London

Another top accounting firm, Baker Tilly is the fastest-growing business on this list. Last year, it announced record revenues of well over $4.5 billion, delivering year-on-year growth of 13%. That’s pretty impressive!

With a network of member firms spanning 145 countries, Baker Tilly serves multinational clients in the audit sector. They offer the following services: 

• Audit and assurance
• Advisory
• Corporate finance
• Legal
• Tax

Baker Tilly also offers industry-specific expertise in global private equity, government and not-for-profits, real estate, and construction. 

9. Crowe Global

Revenue: $4.4 billion

Employees: 42,000

HQ: New York City, USA

Another one of the top accounting firms in the world, Crowe is a network comprising well over 200 firms across 130 countries. Like many of its competitors outside the Big Four, Crowe largely serves middle-market clients. It offers the following services: 

• Audit and accounting services
• Tax 
• Advisory
• Risk consulting

Crowe has a strong focus on industry specialisation, covering areas such as healthcare, financial services, and manufacturing. With their wide international reach, they also offer deep expertise in local markets. 

10. Nexia International

Revenue: $4 billion

Employees: 26,000

HQ: London, UK

Wrapping up this list of top accounting firms is Nexia International. This firm operates in over 120 countries worldwide, providing clients with global reach and local knowledge. Their services include: 

• Audit
• Advisory
• Tax

Their audit service is built on industry-specific knowledge, a deep understanding of global trends, and a focus on technology-driven success. As one of the top-ten largest accounting firms in the world, Nexia serves a range of industries, including healthcare, technology, retail, and financial services.