The Moscone-Knox Act: The Statute Behind Every California Professional Corporation
The Moscone-Knox Professional Corporations Act — California Corporations Code section 13400 and following — is the statute that creates the professional corporation: the required entity form for licensed practices. It restricts ownership to licensed professionals, sets governance and naming rules, and hands each profession’s licensing board authority over its own corporations.
Why You’re Reading About This Statute
Nobody searches for a fifty-year-old corporations statute recreationally. The Act’s name reached you through one of a few doors: it’s cited in your articles of incorporation or bylaws; a lawyer or this site said “Moscone-Knox requires” something about your ownership or governance; a diligence memo flagged it; or you’re comparing sources on how California professional corporations work. Whichever door — the Act rewards ten minutes of actual understanding, because it’s the answer to most “why can’t we just…” questions in California practice structuring.
What Is the Moscone-Knox Professional Corporations Act?
The Moscone-Knox Professional Corporations Act is the part of the California Corporations Code — section 13400 and following — that establishes the professional corporation as the entity form through which licensed professionals may practice via a corporation. Enacted in the late 1960s and amended many times since, it works as a framework statute: it sets the general rules for all professional corporations, then coordinates with each profession’s provisions in the Business and Professions Code and each licensing board’s regulations for the profession-specific details.
The useful mental model: Moscone-Knox is the chassis, and each profession bolts its own rules onto it. A professional medical corporation is Moscone-Knox plus the Medical Practice Act’s provisions plus Medical Board rules; a professional nursing corporation is the same chassis with the Nursing Practice Act and Board of Registered Nursing rules attached. That’s why this site keeps saying “verify the profession’s rules” — the Act deliberately leaves the last mile to each board.
The Five Things Moscone-Knox Actually Does
Strip the statute to its functions and there are five:
- It creates the vehicle. Licensed professionals may practice through a corporation — but only this kind: a professional corporation formed under the Act and registered per the profession’s rules.
- It locks the cap table. Shares may be held only by qualified licensed persons — the rule that makes non-licensee ownership impossible and minority-licensee ownership a defined, capped exception. (The caps, in full: Who Can Own a California Medical Corporation? →)
- It reaches into governance. Licensure requirements follow the shares into the boardroom — directors and officers generally must be qualified licensees, with narrow small-corporation exceptions.
- It plans for disqualification. The Act anticipates the events ordinary corporate law doesn’t: a shareholder who dies or becomes disqualified (license loss, most importantly) triggers mandatory share-transfer mechanics on a statutory clock — which is why compliant PCs need buy-sell and transfer machinery drafted in advance.
- It deputizes the boards. Naming rules, registration requirements, and profession-specific conditions are delegated to each licensing board — the reason a medical corporation and a nursing corporation follow different board playbooks on the same statutory chassis.
The Translation Table
The statute’s key commands, translated into plain English and action.
| What the Act says (in substance) | What it means in plain English | What you do about it |
|---|---|---|
| Professional services through a corporation only via a professional corporation | Your practice entity is a PC — not an LLC, not a standard corporation | Form the right entity; convert if you didn’t (see: PC vs LLC →) |
| Shares held only by qualified licensed persons | The cap table is a compliance document — no founders, funds, or family without the license | Route non-licensee participation through an MSO (see: MSO Structures →) |
| Minority ownership by listed other licensees, within caps | Some cross-profession co-ownership is allowed, defined and limited | Check the current statutory list and limits before promising equity (see: Ownership Rules →) |
| Directors and officers generally licensed | Governance seats carry licensure requirements | Build leadership and succession around qualified people |
| Death or disqualification triggers mandatory transfer on a statutory timeline | The Act forces the question groups avoid: what happens to the shares when something happens to the shareholder | Draft buy-sell and transfer mechanics at formation, not at the event |
| Profession-specific rules per each board | The Act is the chassis; your board supplies the last mile | Verify naming, registration, and profession rules with the actual board — always current, never assumed |
Moscone-Knox and CPOM: Two Halves of One Rule
The Act and the corporate practice of medicine doctrine are teammates, not synonyms — and confusing them muddles analysis:
- Moscone-Knox is the entity half: if licensed practice runs through a corporation, here is the only corporation it may be, and here is who may own and govern it.
- CPOM is the control half: whoever the paperwork says owns it, unlicensed persons and entities may not control the practice of medicine — substance over form.
A structure can satisfy the Act perfectly — right entity, compliant cap table — and still violate CPOM because control migrated to the business side. That’s why every serious review reads both halves: the entity against Moscone-Knox, the arrangement against CPOM. (The control half, in full: Corporate Practice of Medicine →)
What It Means for You, by Chair
Physicians and licensees: the Act is why your entity, cap table, and board seats have rules ordinary businesses don’t — and why events like a partner’s license problem have statutory consequences your documents need to anticipate. (Your entity page: Medical Corporations → · Nursing Corporations →)
Founders and investors: the Act is the specific statute closing practice equity to you — not a board policy or a lawyer’s caution. Your lawful position is the MSO side, and the Act is one reason the two-entity model exists at all. (The model: MSO vs PC Strategy →)
Groups and platforms: the Act’s disqualification mechanics and governance rules are why transfer restrictions, buy-sell agreements, and succession planning are compliance infrastructure here, not optional sophistication.
Three Moscone-Knox Mistakes
- The wrong chassis — an LLC or standard corporation holding licensed practice; the Act’s threshold rule, missed. (See: PC vs LLC →)
- The quiet non-licensee — a founder, spouse, or fund on the cap table in any form; there is no small exception.
- No disqualification machinery — the statutory transfer clock arrives at the worst moment in a shareholder’s life, and the corporation has nothing drafted to meet it.
How MedBiz Law Helps
Moscone-Knox compliance is the entity layer of everything we build: formations on the right chassis, cap tables that stay lawful, governance that satisfies the licensure rules, and the transfer machinery the Act assumes you have. If the translation table raised a row you can’t answer for your own corporation, that row is the review.
Legal services are provided by Bay Legal, PC, a California law firm.
Common Questions
What is the Moscone-Knox Professional Corporations Act in simple terms?
Where is the Moscone-Knox Act in the code?
Does Moscone-Knox apply to my profession?
Is Moscone-Knox the same as the corporate practice of medicine?
What happens to shares if a shareholder loses their license?
Can Moscone-Knox rules be waived by agreement?
The Act, Applied to Your Corporation
Six rows in the translation table — if any of them is an open question for your entity, it’s answerable in one review.
Explore Professional Corporations → · Read FAQs →
Corp. Code § 13400 et seq. — read the statute at leginfo.legislature.ca.gov →
MedBiz Law addresses California law only. Healthcare-business laws differ significantly by state.