The Regulatory Patchwork: Reading Sidley Austin on Jurisdictional MSO Design

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The Regulatory Patchwork: Reading Sidley Austin on Jurisdictional MSO Design

Sidley Austin's healthcare regulatory practice has been mapping the state-by-state architecture of corporate practice and management services organization design. The institutional read is that the patchwork is solvable, but only if the architecture is designed to the most restrictive applicable state from the outset.

By Mike Claudio, Co-Founder, Guardian Tax Consultants® · November 25, 2025 · 8 min read

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Sidley Austin's healthcare regulatory team has been one of the more disciplined voices documenting how state regulators are reading Management Services Organization architecture in 2026. Their recent update on the California Attorney General's amicus posture in the friendly professional corporation cases, authored by Jon S. Zucker, George Maliha M.D., and Mariya Denisenko, is worth reading in full for anyone underwriting an MSO that touches a regulated profession across state lines. The technical mapping is rigorous. What we want to add is the operational-design overlay: the patchwork Sidley describes is solvable, but the architecture has to be designed for the most restrictive applicable state from the start, not retrofitted after the first regulatory letter arrives.

The framing Sidley has put on the regulatory patchwork

Sidley's June 2026 update on the California Attorney General's review of the friendly professional corporation model sets up the analytical baseline cleanly. The authors note, in their words, that "the vast majority of states accept the friendly PC model" as a balanced approach to protecting clinical decision-making while permitting outside investment. Against that backdrop, California's posture is being read as a categorical shift, with the Attorney General arguing that arrangements giving a nonprofessional corporation the right to replace a physician-owner constitute impermissible control over a captive medical practice. The technical question Sidley frames is not whether MSO structures remain viable in California. It is whether the specific design features that work in most other states survive a categorical reading of the corporate practice of medicine doctrine in a state that has now signaled it intends to enforce one.

That framing matters because it makes the design problem visible. A multi-state operating business cannot rely on the modal state's acceptance of a structural feature when one of the states it operates in has moved against that feature. The Sidley update treats the California posture as a meaningful regulatory development that platform sponsors should monitor, alongside the prior 2025 legislation the firm tracked in companion updates. The implied design conclusion is one we agree with: the patchwork is no longer a manageable footnote in the diligence file. It is a primary architectural input.

Why state-by-state design constraints are structural

The state-by-state nature of the constraint is not a transitional artifact. Corporate practice of medicine, corporate practice of law, fee-splitting, and licensure-independence rules sit inside state professional licensing statutes and state bar or medical board interpretations. Federal preemption is not a realistic backstop. The American Medical Association's published commentary on Oregon's 2025 corporate practice statute reinforces the point: state legislatures and state attorneys general are moving independently, and the variation between jurisdictions is widening rather than narrowing. The structural reality Sidley's update implies, and that the AMA's commentary makes explicit, is that any MSO architecture touching a regulated profession in more than one state has to be designed against a moving baseline.

The structural exposure compounds where the underlying federal tax architecture also has to hold. The related-party services fee that the MSO charges the operating professional entity is evaluated under Internal Revenue Code §482, deducted under §162, and assessed against the personal-service-corporation reallocation authority in §269A. The federal substantiation file is built once, and it is built to one standard. The state regulatory file has to be built fifty times, against fifty potentially divergent standards, and reviewed continuously as state law moves. That is the asymmetry that makes the jurisdictional design problem the hardest part of a multi-state MSO build.

The "design to the most restrictive state" principle

The operational discipline that follows from Sidley's framing is the one we apply to every multi-state MSO build: the architecture is designed to comply with the most restrictive applicable state, not the most permissive. That principle sounds obvious until it runs into the economics of the deal. A friendly PC model that works cleanly in thirty-five states but requires a continuity agreement structure the California Attorney General has now characterized as impermissible control is not a thirty-five-state structure. It is an architectural fork in the road. Either the design is rebuilt to satisfy California's posture across the whole footprint, with the economic and governance trade-offs that implies, or California is carved out of the footprint, with the operational complexity that implies, or the architecture is split into a multi-entity structure that holds different design features in different jurisdictions, with the substantiation complexity that implies.

None of those three paths is wrong. All three are defensible if the design discipline is applied at formation. What does not work is the fourth path, which is the one platforms most often default into: building the structure to the modal state's standard, expanding into a restrictive state opportunistically, and addressing the regulatory mismatch reactively when an inquiry arrives. That path is the one that produces the litigation Sidley is now mapping. The architectural cost of designing to the most restrictive state at formation is real, but it is bounded. The cost of retrofitting a multi-state architecture under regulatory pressure is not.

Where GTC's institutional read adds operational discipline

Sidley's regulatory mapping is the right starting point. What we add to the deal team's working file is the operational-discipline layer underneath it. Three observations from our practice on multi-state MSO builds for closely-held operating businesses and platform sponsors.

First, the governance documents have to mirror the regulatory file. Where a state's posture treats certain control features as impermissible, those features cannot live in the management services agreement, in side letters, in the continuity agreement, or in informal practice. The Sidley update on the California cases is instructive precisely because the issue was a continuity agreement feature, not a fee mechanic. State regulators read the documents as a whole. So does the IRS when it looks at the §482 substantiation file. A platform that has clean federal tax documentation and a state-level control feature buried in a continuity agreement is not a clean platform. It is two platforms in different states of regulatory hygiene.

Second, the substantiation file has to be portable across the regulatory standards it has to satisfy. The functional analysis underlying the related-party services fee documents what the MSO actually does, what personnel render the services, and what assets and risks the MSO bears. That functional analysis is the same document that demonstrates, to a state regulator, that the MSO is performing administrative services rather than exercising clinical, legal, or other professional judgment. A single, well-built functional analysis serves both audiences. A federal-only file leaves the state question unanswered, which is the gap a state regulator will read against the platform.

Third, the cross-disciplinary coordination at formation is what makes the structure survive scrutiny in any individual state. The same Sidley update is consistent with our read across the law firm MSO structures sponsored capital is now building: the regulatory layer and the tax layer have to be designed jointly, and the deal team's related-party transfer pricing analysis has to be readable as the same document by a state regulator and by an IRS examiner. The Handler & Wells Hall memorandum tradition on related-party services in MSO structures is one we apply with the state regulatory overlay as a co-equal input, not a downstream check.

One framing point worth keeping in view: the principle that an MSO architecture must comply with the most restrictive applicable state is not unique to corporate practice of medicine. The same discipline applies, with different specifics, to the corporate practice of law in jurisdictions that have not adopted the alternative business structure reforms, to fee-splitting rules under the American Bar Association Model Rules as adopted at the state level, to licensure independence rules across regulated professions, and to state insurance and securities licensing rules where the MSO platform touches those activities. Sidley's healthcare-focused update on the California posture is the prompt; the architectural principle generalizes.

The closing observation

Sidley's institutional framing of the regulatory patchwork is the technically rigorous baseline the deal community needs. What the framing implies, and what we want to make explicit for the deal teams and family-office planners reading our notes, is that the state-by-state design problem is solvable but it has to be solved upfront. Retrofitting a multi-state MSO to fix a state-specific compliance issue is materially harder than designing the architecture correctly at formation. The platforms that survive a categorical state-level reading of the corporate practice doctrine are the ones whose governance documents, related-party services file, and operational controls were all designed to the same standard the most restrictive applicable state would apply, before the platform expanded into that state. The architectural decision sits at formation. Everything after formation is enforcement of the decision the architecture already made.

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