List of accounting firms: the largest, how many there are, and how to build your own from state and PCAOB records

This guide is for companies that sell to accounting firms: tax, audit and practice management software, IT and cybersecurity providers, staffing and recruiting firms, professional liability insurers and firms that buy or merge practices. It also helps anyone who wants to know which accounting firms are largest or check a particular firm. It covers how many firms there are, the largest networks, the official registries and how accounting firms buy.

How many accounting firms there are

County Business Patterns, the Census Bureau's count of business locations with paid employees, found 137,069 accounting, tax preparation, bookkeeping and payroll establishments (NAICS 5412) in 2023, employing 1,297,995 people.

CPA offices are mostly small:

Size bands add up to slightly less than the total because Census withholds a few state figures. These are locations, not firms: a national firm with 40 offices counts 40 times, and sole practitioners with no employees aren't counted at all.

The largest accounting firms

The four largest networks report global revenue each year. Each is a network of separately owned member firms, so the figures combine many countries.

Rankings of US firms by US revenue, such as Accounting Today's annual Top 100, are published by trade magazines and usually require registration to read. Use them for names; use the registries below for coverage.

PCAOB-registered firms: who audits public companies

Any firm that audits a US-listed company or an SEC-registered broker-dealer must register with the Public Company Accounting Oversight Board. At the end of 2025, 1,444 firms were registered: 646 in the US and 798 in 80 other jurisdictions, down 6% from 1,544 a year earlier.

So only 194 US firms signed an audit report on a public company, and a dozen do most of that work. If you sell audit tools or services tied to public company work, that's the whole market. Each public company's annual report includes its auditor's report, which names the firm.

State boards of accountancy: the master list

A CPA is licensed by a state board of accountancy, and a CPA firm must register with the board in each state where its professionals practice. That makes the boards the most complete list of CPA firms.

• CPAverify. NASBA, the national association of state boards, runs CPAverify, a free national lookup of licensed CPAs and CPA firms built from data the boards supply. It's the quickest way to check a firm.
• State downloads. Some boards publish their lists. Virginia's board, for example, lets you search CPA firms by name, license number or ZIP code and download results as XML or delimited text.
• Rules on use. Some boards restrict commercial use of their lists. Read the terms before you load one into a sales tool.

How accounting firms buy

• Partners decide. Most CPA firms are partnerships. The managing partner signs, but big changes often need a partner vote, and a skeptical partner can stall a deal.
• A firm administrator runs the process. Firms with more than about 20 staff often have a firm administrator or COO who evaluates vendors, and larger firms add an IT director.
• Busy season rules the calendar. Individual returns are due on 15 April, with an automatic six-month extension to October. From January to mid-April, partners won't take your call.
• Security is a legal issue. The FTC Safeguards Rule names tax preparation services as financial institutions, so they must run a written security program with a Qualified Individual and multi-factor authentication. See selling IT services for what the rule requires.
• Peers decide. Firms join associations and networks of independent firms, and they trust what other firms of their size use.

Segment the list

• Type. Audit and assurance, tax, outsourced bookkeeping and advisory, or payroll. Tax-only shops buy differently from audit firms.
• Size. Sole practitioners, small firms (5 to 19), regional firms (20 to 499) and national firms.
• Regulated work. PCAOB registration, broker-dealer audits or government audits each bring their own tools and rules.
• Niche. Many firms specialize by client industry (construction, nonprofits, health care). Their websites say so.
• Ownership. A firm that has just merged or taken outside investment is often replacing systems.

Worked example: CPA firms in Virginia

Illustrative example. The seller and its plan are fictional; the counts come from County Business Patterns 2023.

The seller: Ledgerbridge (ledgerbridge.example) sells client portal and workflow software for CPA firms. The goal: firms large enough to have a firm administrator, in one state.

1. Size the market. Virginia has 1,183 CPA offices, and 172 of them have 10 to 49 employees.
2. Get the names. Download Virginia's active CPA firm list from the board's portal and match firms to websites. Check the board's terms on commercial use first.
3. Find the people. Two contacts per firm: the managing partner and the firm administrator, from each firm's team page. That's 344 contacts.
4. Time it. Start in late April, after the filing deadline. At an illustrative 10% reply rate, that's 34 conversations; if an illustrative quarter of those start a trial over the summer, 8 trials before the next busy season.
5. Write to the season. Acknowledge what they've just been through:

Subject: Before next busy season at [firm]

Hi [first name],

Congratulations on getting through April. I imagine the last thing you want is another tool, so I'll be brief.

Firms your size tell us their worst busy-season hours go on chasing clients for documents and signatures by email.

We help firms like [firm] [outcome, e.g. collect documents and e-signatures through one client portal]. If that's on your list for the summer, could I show you in 20 minutes in May?

[Your name]

Finding the managing partner and firm administrator at each firm is the slow part at volume; Bebop finds matching firms and contacts and writes a playbook for each account.

Common mistakes

• Pitching in busy season. Anything sent from January to mid-April is ignored or resented.
• Selling to one partner. Expect the decision to go to the partner group.
• Using a top 100 list as a prospect list. The largest firms buy through procurement; the market is tens of thousands of small firms.
• Counting offices as firms. County Business Patterns counts locations.
• Ignoring security rules. Tax preparers face the Safeguards Rule; show how you help them meet it.

Next step: write down the firm type, size and region you sell to with the ideal customer profile template, then pull the matching firms from your state board's list.