A physician earning $400,000 through a private practice structured as a C Corporation paid $167,400 in combined federal and California taxes last year. The same physician, restructured as an S Corporation with a $180,000 reasonable salary, would have owed $118,600. That is a $48,800 gap created by one entity election most doctors never file. The question of whether a C or S Corp is better for physicians is not theoretical. It is the single biggest financial decision a California doctor will make outside of buying a home or choosing a specialty.

And most physicians get it wrong. Not because they lack intelligence, but because they rely on attorneys who default to C Corps during incorporation and never revisit the decision once the practice starts generating real income. By the time the doctor notices the tax drag, years of overpayment have already stacked up.

Quick Answer: Is a C or S Corp Better for Physicians?

For the vast majority of California physicians earning $200,000 or more through a private practice or professional corporation, an S Corporation produces significantly lower total taxes than a C Corporation. The S Corp eliminates federal corporate-level tax, avoids double taxation on distributed profits, unlocks the 20% Qualified Business Income (QBI) deduction under IRC Section 199A, reduces California franchise tax from 8.84% to 1.5%, and activates the AB 150 Pass-Through Entity (PTE) tax election to bypass the $40,000 SALT cap. The only narrow exceptions involve practices actively seeking venture capital, retaining 100% of earnings below $250,000 annually, or pursuing Qualified Small Business Stock (QSBS) benefits under IRC Section 1202.

Why Most California Physicians Stay in the Wrong Entity Structure

The problem starts at formation. When a physician incorporates a medical practice in California, the default entity is a professional corporation taxed as a C Corp. The attorney files Articles of Incorporation with the California Secretary of State, obtains an EIN from the IRS, and hands the doctor a stack of corporate documents. Nobody mentions Form 2553, the IRS election that converts the corporation’s tax treatment to S Corp status.

The result is a practice that pays federal corporate tax at 21% on every dollar of profit, then pays tax again when those profits are distributed as dividends. California adds its own 8.84% franchise tax on top of the federal layer, creating a combined effective tax rate that regularly exceeds 45% for physicians earning between $300,000 and $600,000.

Many medical professionals assume their CPA is handling entity optimization. But most CPAs prepare the returns they receive. If the practice was formed as a C Corp, the CPA files a Form 1120 and moves on. The conversation about whether a C or S Corp is better for physicians never happens unless the doctor initiates it.

The Three Formation Traps Physicians Fall Into

• Attorney default: Business attorneys form professional corporations as C Corps because that is the standard template. They are not tax strategists, and their job ends at incorporation.
• CPA passivity: Most CPAs file whatever entity return matches the current structure. They rarely proactively recommend a structural change because it creates additional work and liability.
• Physician time poverty: Doctors work 50 to 70 hours per week seeing patients. Financial planning gets compressed into a 30-minute annual meeting that barely covers retirement contributions, let alone entity restructuring.

The Five-Layer Tax Comparison: C Corp vs S Corp for Physicians

Understanding why an S Corp wins for most physicians requires examining five distinct tax layers. A single-rate comparison between the 21% corporate rate and the 37% individual rate is misleading because it ignores four additional costs that stack on top of C Corp taxation.

Layer 1: Federal Entity-Level Tax

A C Corporation pays 21% federal tax on all net profits. An S Corporation pays 0% at the entity level because profits pass through to the shareholder’s individual return. For a physician practice earning $350,000 in net profit, that is $73,500 in federal corporate tax the C Corp pays before a single dollar reaches the doctor’s personal bank account. The S Corp owes nothing at the entity level.

Layer 2: Federal Dividend Double Taxation

After the C Corp pays its 21% tax, the remaining $276,500 is distributed to the physician as a qualified dividend. That dividend is taxed at 15% to 23.8% depending on the doctor’s total income (including the 3.8% Net Investment Income Tax under IRC Section 1411). At 23.8%, that creates an additional $65,807 in federal tax on the dividend. The S Corp avoids this entirely because distributions from an S Corp are not subject to double taxation.

Layer 3: California Franchise Tax Differential

California taxes C Corporations at 8.84% of net income. S Corporations pay just 1.5%. On $350,000 of practice profit, the C Corp owes $30,940 in California franchise tax while the S Corp owes $5,250. That is a $25,690 state-level gap that grows every year the physician stays in the wrong structure. This layer alone can fund a full year of retirement contributions.

Layer 4: QBI Deduction Exclusivity

The Qualified Business Income deduction under IRC Section 199A allows S Corp shareholders to deduct up to 20% of their qualified business income from their federal taxable income. This deduction was made permanent under the One Big Beautiful Bill Act (OBBBA) signed into law in 2025. C Corporation shareholders receive zero QBI benefit because the deduction is exclusively available to pass-through entities. For a physician with $350,000 in S Corp income after a reasonable salary of $180,000, the QBI deduction on the remaining $170,000 of pass-through income saves approximately $10,200 in federal taxes (at a 30% marginal rate on a $34,000 deduction). For a complete breakdown of how S Corp elections interact with QBI optimization, see our comprehensive S Corp tax strategy guide.

However, physicians must watch the Specified Service Trade or Business (SSTB) limitation. Medical practices are classified as SSTBs under IRC 199A(d)(2), which means the QBI deduction phases out for single filers between $197,300 and $247,300, and for married filing jointly between $394,600 and $494,600 (2026 thresholds). Physicians below these thresholds capture the full benefit. Those above may lose it entirely.

Layer 5: AB 150 PTE Tax Election

California’s AB 150 Pass-Through Entity tax election allows S Corp shareholders to bypass the $40,000 SALT (State and Local Tax) deduction cap imposed by OBBBA. The S Corporation pays state tax at the entity level and claims a dollar-for-dollar credit on the shareholder’s personal return. This converts a non-deductible state tax payment into a fully deductible business expense. For a physician in the 37% federal bracket, the AB 150 election on $5,250 of California S Corp tax saves approximately $1,942 in federal taxes. C Corporations cannot use AB 150 because the election is exclusive to pass-through entities.

Side-by-Side Comparison at $350,000 Practice Profit

Tax Layer	C Corporation	S Corporation
Federal Entity Tax	$73,500 (21%)	$0 (0%)
Federal Dividend/Income Tax	$65,807 (23.8% on distributions)	$59,500 (individual rates on pass-through)
California Franchise Tax	$30,940 (8.84%)	$5,250 (1.5%)
QBI Deduction Savings	$0	Up to $10,200
AB 150 PTE Savings	$0	$1,942
Total Tax Burden	$170,247	$113,608
Annual Gap	$56,639 S Corp Advantage

Want to run your own practice profit through a detailed analysis? Plug your numbers into this small business tax calculator to estimate your total tax exposure under both structures.

The Five Costliest Entity Mistakes Physicians Make

Choosing the wrong entity is only the beginning. Even physicians who recognize the S Corp advantage often make implementation errors that erode their savings or trigger IRS scrutiny.

Mistake 1: Setting an Unreasonable Salary ($12,000 to $47,000 Exposure)

The IRS requires S Corp shareholder-employees to pay themselves a “reasonable salary” before taking distributions. For physicians, reasonable salary benchmarks are high. A family medicine physician’s reasonable salary might range from $180,000 to $230,000 depending on geography and specialty. An orthopedic surgeon’s reasonable salary could exceed $350,000. Setting salary too low triggers IRS reclassification of distributions as wages, plus back payroll taxes, penalties, and interest. The landmark case Watson v. Commissioner established that the IRS will aggressively pursue unreasonably low salaries. Setting salary too high eliminates the self-employment tax savings that make the S Corp election worthwhile.

Mistake 2: Missing the Form 2553 Deadline ($24,000+ Annual Cost)

Form 2553 must be filed within 75 days of the start of the tax year for the S Corp election to take effect that year. Physicians who miss this deadline lose an entire year of S Corp benefits. At $350,000 in practice profit, that is $56,639 in unnecessary taxes for a single missed deadline. Rev. Proc. 2013-30 provides late election relief, but only if the physician can demonstrate reasonable cause and files within 3 years and 75 days.

Mistake 3: Ignoring California Bonus Depreciation Nonconformity ($3,000 to $15,000 Annual Cost)

OBBBA restored 100% federal bonus depreciation permanently. California does not conform to this provision under Revenue and Taxation Code Sections 17250 and 24356. Physicians who purchase medical equipment, office furniture, or imaging machines and claim full bonus depreciation federally must maintain separate California depreciation schedules. Failing to do so results in either underpaying California taxes (triggering penalties) or overpaying (leaving money on the table).

Mistake 4: Skipping the AB 150 PTE Election ($1,500 to $8,000 Annual Cost)

Many physicians who successfully elect S Corp status never file for the AB 150 PTE election. This optional election must be made annually and requires the S Corporation to pay the PTE tax at the entity level. The physician then claims a credit on their personal California return. Without it, the SALT cap limits the physician’s state tax deduction to $40,000 regardless of how much California tax they actually pay. Our tax planning services help physicians identify and activate every available election before year-end deadlines pass.

Mistake 5: Failing to Track Basis on Form 7203 ($5,000 to $25,000 Exposure)

Starting in 2021, the IRS requires S Corp shareholders to file Form 7203 (S Corporation Shareholder Stock and Debt Basis Limitations) with their individual return. This form tracks the physician’s stock and debt basis in the S Corporation and determines the deductibility of losses and the tax treatment of distributions. Physicians who skip this form risk distributions being reclassified as taxable income, creating unexpected tax bills and potential accuracy-related penalties under IRC Section 6662 at 20% of the underpayment.

KDA Case Study: Sacramento Dermatologist Saves $48,800 in Year One

Dr. Sarah Chen (name changed for privacy) operated a solo dermatology practice in Sacramento structured as a C Corporation since 2019. Her practice generated $420,000 in annual net profit. Under the C Corp structure, she paid $176,400 in combined federal and California taxes after accounting for corporate tax, dividend taxation, and the 8.84% California franchise tax rate. Her CPA filed Form 1120 every year without questioning the entity structure.

When Dr. Chen engaged KDA in early 2026, we identified the five-layer tax gap immediately. Our team filed Form 2553 for late S Corp election relief under Rev. Proc. 2013-30, set her reasonable salary at $210,000 based on MGMA dermatology compensation data, activated the AB 150 PTE election, established dual federal and California depreciation schedules for $85,000 in recently purchased laser equipment, and coordinated a Solo 401(k) contribution of $23,500 to further reduce taxable income.

The result: Dr. Chen’s total tax liability dropped to $127,600 in year one, a savings of $48,800. She paid KDA $5,800 for the full restructuring engagement, producing an 8.4x first-year return on investment. Over five years, the projected savings total $244,000 assuming stable practice income. The restructuring took six weeks from engagement to completion, and Dr. Chen did not miss a single patient appointment during the process.

Ready to see how we can help you? Explore more success stories on our case studies page to discover proven strategies that have saved our clients thousands in taxes.

Three Narrow Scenarios Where a C Corp Wins for Physicians

The S Corp advantage is overwhelming for most physician practices, but three specific situations create a legitimate case for maintaining C Corp status. If none of these apply to you, the S Corp wins every time.

Scenario 1: Venture Capital or Private Equity Investment

If your practice is being acquired by or merging with a private equity-backed platform (increasingly common in ophthalmology, dermatology, and gastroenterology), the acquiring entity almost always requires C Corp status. Institutional investors need the flexibility of multiple share classes and unlimited shareholders that only C Corps provide. If you have a signed letter of intent from a PE firm, maintaining C Corp status during the transaction makes sense. But if the deal is hypothetical, the S Corp savings are real today.

Scenario 2: QSBS Under IRC Section 1202

Qualified Small Business Stock allows C Corp shareholders to exclude up to $10 million in capital gains (or 10 times their basis) when selling shares held for more than five years. OBBBA expanded QSBS by adding new exclusion tiers. However, California does not conform to the federal QSBS exclusion under R&TC Section 18152.5, meaning the physician would still owe California’s 13.3% capital gains rate on the full gain. Additionally, medical practices classified as health-related SSTBs may face limitations on QSBS eligibility depending on how the practice income is categorized.

Scenario 3: Full Profit Retention Below $250,000

If the physician retains 100% of practice profits inside the corporation and takes zero distributions, the C Corp’s 21% flat rate can appear lower than individual rates. But this strategy has a hard ceiling. The accumulated earnings tax under IRC Section 531 imposes a 20% penalty tax on retained earnings above $250,000 that the IRS determines have no reasonable business purpose. For a physician practice with limited capital needs, hitting this threshold takes only one to two years of full retention.

The 8-Step C Corp to S Corp Conversion Process for Physicians

Physicians currently operating as C Corps can convert to S Corp status without forming a new entity. The existing professional corporation remains intact. Only the federal and state tax elections change.

1. Verify S Corp eligibility under IRC 1361(b): The corporation must have 100 or fewer shareholders, all of whom are U.S. citizens or residents. Only one class of stock is permitted. Most solo and small group physician practices qualify automatically.
2. Evaluate Built-In Gains (BIG) tax exposure under IRC 1374: If the C Corp holds appreciated assets (real estate, equipment, goodwill), a five-year BIG recognition period applies after conversion. During this window, gains on assets held at the time of conversion are taxed at the corporate rate. Calculate the potential BIG tax exposure before filing.
3. Calculate and address Accumulated Earnings and Profits (AE&P): C Corps accumulate earnings and profits under IRC Section 312. After conversion, AE&P can cause S Corp distributions to be recharacterized as taxable dividends under IRC 1368(c). Distributing AE&P before or during conversion eliminates this risk. The bypass election under IRC 1368(e)(3) provides an alternative ordering rule.
4. File Form 2553 with the IRS: Submit the election by March 15 of the tax year for it to take effect that year. All shareholders must consent. For late elections, attach a statement under Rev. Proc. 2013-30 demonstrating reasonable cause.
5. File FTB Form 3560 with California: California requires a separate S Corp election filing with the Franchise Tax Board. The federal election alone does not automatically apply to California. Missing this step means the practice remains a C Corp for state tax purposes even if the IRS recognizes S Corp status.
6. Establish reasonable salary and payroll: Set the physician’s W-2 salary based on specialty-specific compensation benchmarks (MGMA, AMGA, or SullivanCotter data). Register with the California EDD for payroll tax withholding. Run payroll at least monthly.
7. Activate the AB 150 PTE election: File the annual PTE election before the June 15 estimated tax deadline. The S Corporation pays California tax at the entity level and the physician claims the credit on Form 540.
8. Set up dual depreciation schedules: Because California does not conform to federal bonus depreciation under R&TC Sections 17250 and 24356, the practice must maintain separate federal and California depreciation schedules for all assets. This applies to medical equipment, office buildouts, imaging machines, and any other depreciable property.

OBBBA Permanent Changes That Affect the C or S Corp Decision for Physicians

The One Big Beautiful Bill Act made several provisions permanent that directly influence entity selection for physician practices in 2026 and beyond.

• QBI deduction (IRC 199A) is permanent: The 20% pass-through deduction is no longer at risk of expiration. S Corp physicians below the SSTB threshold can rely on this deduction for long-term planning. C Corp physicians receive zero QBI benefit, permanently.
• 100% bonus depreciation is restored: After phasing down to 60% in 2024 and 40% in 2025, full bonus depreciation was restored permanently under OBBBA. Physicians purchasing equipment can deduct the entire cost in year one federally. California still does not conform.
• Section 179 limit increased to $2.5 million: The expensing limit for qualifying assets was raised permanently. This benefits physician practices investing in imaging equipment, surgical tools, and office technology.
• SALT cap set at $40,000: OBBBA made the SALT cap permanent at $40,000 (up from $10,000). Without the AB 150 PTE election, California physicians lose the ability to deduct state taxes above this amount. The PTE election is the only workaround for S Corp practices.
• Estate tax exemption raised to $15 million: Physician practice owners planning generational transfers benefit from the increased exemption, particularly when combined with irrevocable trust structures.

What About the SSTB Phase-Out? Can Physicians Still Claim QBI?

This is the most common follow-up question physicians ask after learning about the S Corp advantage. Medical practices are classified as Specified Service Trades or Businesses under IRC 199A(d)(2), which means the QBI deduction phases out at higher income levels.

For 2026, the phase-out ranges are:

• Single filers: QBI deduction begins phasing out at $197,300 and disappears completely above $247,300 of taxable income.
• Married filing jointly: Phase-out begins at $394,600 and disappears above $494,600 of taxable income.

A married physician with a spouse who earns little or no income and total taxable income below $394,600 after deductions captures the full QBI benefit. A dual-physician household earning $700,000 combined likely loses QBI entirely. The key variable is taxable income after all deductions, not gross practice revenue. Maximizing retirement contributions (Solo 401(k) at $72,000 combined employer and employee for physicians over 50), HSA contributions ($8,750 family limit in 2026), and other above-the-line deductions can bring taxable income below the threshold.

Even when QBI phases out completely, the S Corp still wins on the other four layers: zero entity-level federal tax, no double taxation, lower California franchise tax, and AB 150 PTE access. The QBI deduction is a bonus, not the foundation of the S Corp case for physicians.

Will Switching to an S Corp Trigger an IRS Audit?

No. Filing Form 2553 to elect S Corp status is a routine administrative election, not a red flag. The IRS processes approximately 500,000 S Corp elections annually. What does trigger scrutiny is the salary-to-distribution ratio after the election takes effect. The IRS Palantir SNAP AI system cross-references S Corp payroll data against industry compensation benchmarks. A physician claiming $80,000 in salary while taking $300,000 in distributions will be flagged faster than a physician paying $210,000 in salary with $110,000 in distributions.

The safest approach: use published specialty compensation data from MGMA or AMGA to set salary at the median for your specialty and geography. Document the salary calculation in your corporate minutes. Keep the documentation for at least seven years.

Frequently Asked Questions

Can a physician practice be an S Corp in California?

Yes. California permits professional corporations (including medical corporations formed under the Moscone-Knox Professional Corporation Act) to elect S Corp status. The physician files Form 2553 with the IRS and Form 3560 with the California FTB. Both filings are required for full S Corp treatment at the federal and state levels.

What is a reasonable salary for a physician S Corp?

Reasonable salary varies by specialty, geography, and hours worked. Use MGMA, AMGA, or SullivanCotter survey data as benchmarks. A family medicine physician in Sacramento might set salary at $190,000 to $220,000. An interventional cardiologist could justify $400,000 or more. The IRS looks at what a comparable physician would earn as an employee performing the same work.

Does the S Corp election affect my medical malpractice liability?

No. The S Corp election changes only the tax treatment of the corporation. It does not alter the physician’s personal liability for malpractice, the corporation’s liability protection, or the professional corporation’s legal structure. Malpractice insurance coverage and corporate veil protections remain identical regardless of whether the practice is taxed as a C Corp or S Corp.

Can I convert back to a C Corp if I change my mind?

You can revoke the S Corp election at any time by filing a revocation statement with the IRS under IRC Section 1362(d)(1). However, once you revoke, the five-year re-election lockout under IRC 1362(g) prevents you from re-electing S Corp status for five full tax years without a Private Letter Ruling (PLR) at $15,300. This makes the conversion decision one that deserves careful analysis before executing in either direction.

What happens to my retirement plan if I switch to S Corp?

Most qualified retirement plans (401(k), defined benefit, profit sharing) transfer without interruption. The plan sponsor entity remains the same corporation. The only change involves contribution calculations. S Corp shareholder-employee retirement contributions are based on W-2 salary, not total practice profit. A Solo 401(k) allows the physician to contribute $23,500 as an employee deferral (plus $7,500 catch-up if over 50) and an additional 25% of W-2 salary as an employer contribution, up to the combined annual limit of $72,000 for 2026.

Is there a minimum income level where the S Corp makes sense for physicians?

The S Corp election becomes beneficial when practice net profit exceeds approximately $80,000 to $100,000 annually. Below that level, the administrative costs of payroll, additional tax filings (Form 1120-S, California Form 100S), and compliance requirements can offset the tax savings. For physicians, this threshold is almost always exceeded within the first year of practice.

This information is current as of 4/24/2026. Tax laws change frequently. Verify updates with the IRS or FTB if reading this later.

The IRS is not hiding these savings from physicians. Your current entity structure is.

Book Your Physician Tax Strategy Session

If your medical practice is still structured as a C Corporation and you have never run the five-layer tax comparison, you are likely overpaying by $25,000 to $60,000 every single year. That is not a rounding error. That is a down payment on a rental property, five years of maxed-out retirement contributions, or your child’s entire college fund. Book a personalized consultation with our physician tax strategy team and walk away with a clear, dollar-specific plan to restructure your practice and keep more of what you earn. Click here to book your consultation now.