The Complete Tax Guide for Physician Practice Owners

At $300,000 in net practice income, an S-corp election typically saves $10,000–$20,000 per year in payroll taxes — one of several decisions that make physician practice owner taxes meaningfully more complex than either employed physicians or typical small business owners. You have entity structure decisions, a salary that must satisfy IRS scrutiny, self-employment and payroll tax interactions, retirement contribution options most CPAs never surface, and a quarterly payment obligation that runs in the background all year.

Most physicians learn these topics reactively — after an unexpected tax bill, an audit notice, or a colleague mentioning something their CPA “set up.” This guide covers the full landscape proactively, with links to detailed analysis on each topic.

1. What Entity Structure Should a Physician Practice Use?

The first tax decision a physician practice owner makes — and the one that affects every subsequent calculation — is how the practice is taxed.

Single-member LLC (default): All net income is self-employment income. You pay SE tax at 15.3% on the first $184,500 (2026) and 2.9% on everything above, plus federal and state income tax.

LLC or corporation with S-corp election: You pay yourself a W-2 salary subject to payroll taxes. Income above the salary flows as K-1 distributions — taxed as ordinary income, but not subject to payroll taxes. The Medicare tax (2.9%) avoided on distributions is the core economic benefit.

The S-corp election makes financial sense once practice net income consistently exceeds approximately $150,000–$175,000 per year. Below that, the compliance costs — payroll, Form 1120-S preparation, state filings — eat the tax savings. Above $200,000, the net benefit grows meaningfully with every additional dollar of practice income.

If your practice is already an LLC and the S-corp election was never filed, the IRS allows retroactive elections under Revenue Procedure 2013-30 for up to 3 years and 75 days after the intended effective date — potentially recovering multiple years of overpaid taxes in a single filing.

Go deeper:

• S-Corp vs. LLC for Physician Practices: The Breakeven Math
• Missed the S-Corp Election Deadline? Here’s How to Fix It Retroactively

2. Why Does Your S-Corp Salary Affect Everything Else?

Once you have an S-corp, one decision determines how much of your income is subject to payroll taxes: your W-2 salary. This is not a set-it-and-forget-it number. It affects your payroll tax burden, your retirement contribution ceiling, and your IRS audit exposure — every single year.

The IRS standard: Reasonable compensation. The IRS uses MGMA specialty survey data to benchmark what you should be paying yourself. Setting your salary below your specialty’s MGMA median without documented justification is an audit flag. Setting it above the optimal level means you are paying unnecessary payroll taxes on the excess.

The formula: Your salary should be the greater of your MGMA specialty median or 40% of practice net income. For a family medicine physician netting $300,000, the MGMA median (~$230,000) controls. For a psychiatrist netting $200,000, salary equals net income — there is nothing to distribute, and the S-corp structure provides limited benefit at that level.

The retirement connection: Your employer profit-sharing contribution to a Solo 401(k) is capped at 25% of your W-2 salary. A $230,000 salary allows up to $57,500 in employer profit sharing. A $100,000 salary caps it at $25,000. The salary decision cascades directly into your maximum retirement deduction — which is often the largest single tax lever available to a physician practice owner.

Go deeper:

• How Much Should I Pay Myself as a Physician S-Corp Owner?
• Free tool: S-Corp Salary Optimizer for Physicians — recommended salary range for your specialty, emailed in 90 seconds

3. How Do Quarterly Estimated Taxes Work for Physician Practice Owners?

The IRS expects taxes to be paid throughout the year as income is earned — not in a lump sum at filing. For S-corp owners, the salary piece is handled through payroll withholding. The K-1 distribution piece is not withheld anywhere. Quarterly estimated payments are required to cover it.

The safe harbor rule: Pay at least 110% of prior year total tax liability (the threshold is 110% — not 100% — for taxpayers with AGI above $150,000, which applies to virtually every physician practice owner). Divide by four. Pay by the quarterly due dates: April 15, June 16, September 15, January 15.

Meeting the safe harbor protects you from the underpayment penalty regardless of how much more you owe at filing.

The W-4 alternative: Physicians who are also employed — hospital W-2 plus practice income — can often eliminate the quarterly payment requirement entirely by increasing withholding on their employer W-4. The IRS treats withholding as paid evenly throughout the year regardless of when it was actually deducted, so sufficient end-of-year withholding cures a quarterly shortfall.

Reserve target: Hold 30%–38% of K-1 distributions in a dedicated tax reserve account. The exact percentage depends on your marginal rate, state, and deductions. Georgia residents at $400,000 in net income should be in the 33%–35% range.

Go deeper:

• Physician Practice Quarterly Estimated Taxes: How Much to Set Aside
• Physician With Both 1099 and W-2 Income: How Taxes Actually Work

4. Which Retirement Accounts Give Physician Practice Owners the Largest Deduction?

No single tax lever produces more savings for physician practice owners than retirement account contributions — and no single lever is more consistently underutilized.

The stack, from simplest to most powerful:

Solo 401(k): Up to $24,500 in employee deferrals ($32,500 if age 50+) plus employer profit sharing of 25% of W-2 salary, subject to a combined limit of $72,000 ($80,000 if 50+). The employer profit-sharing portion is deductible at the practice level, reducing S-corp net income and your personal income tax simultaneously.

Defined Benefit / Cash Balance Plan: The option most CPAs never raise. Actuarially calculated annual contributions based on your age and plan design — ranging from $100,000 at age 45 to $300,000+ at age 60. Stacked on top of a 401(k) in a combination plan. At a 37% federal marginal rate, a $200,000 cash balance contribution produces $74,000 in avoided federal income tax in a single year.

For a physician age 54 running the full stack — Solo 401(k) plus cash balance plan — total annual retirement contributions can reach $280,000+, sheltering over $100,000 in combined federal and state taxes per year.

The window: Cash balance plans work best when funded consistently over many years. Every year you delay starting one is a year of compounding tax savings that cannot be recovered.

Go deeper:

• Physician Practice Retirement Accounts: The Options Most CPAs Don’t Surface

5. How Much Can You Actually Take Out in Practice Distributions?

The practice bank balance is not a personal account. Money in the S-corp belongs to the S-corp until it is formally distributed to you as a shareholder. Taking more than the practice can support creates cash crunches. Taking too little leaves money sitting in a corporate account earning nothing while you carry personal debt.

The distribution capacity formula:

Practice bank balance, minus a two-month operating reserve (2× your fixed monthly expenses), minus a tax reserve on undistributed K-1 income (30%–38%), minus any known large upcoming expenses, equals what you can safely distribute this month.

Run this calculation before every distribution — not on a fixed monthly schedule. Practices with variable collections cycles need the calculation to reflect actual cash, not a calendar.

The IRS constraint: Distributions cannot be taken before a reasonable W-2 salary has been paid. A physician taking $0 in salary and $400,000 in distributions is a textbook audit scenario. The salary must come first; distributions are what remains.

Go deeper:

• How Much Can I Take Out of My Physician Practice S-Corp?

6. What Are the Five Gaps That Cause Most Practices to Overpay?

The most common causes of unexpectedly high physician practice tax bills are not random. The same five structural gaps appear repeatedly:

1. S-corp salary set wrong — either too high (unnecessary payroll taxes) or too low (audit exposure)
2. No retirement contributions, or the wrong vehicle — the defined benefit plan option is almost never surfaced proactively
3. Health insurance premium deduction missed — S-corp owner-employee premiums must flow through payroll to be deductible; when this is mishandled, it disappears
4. Vehicle deduction errors — Section 179 requires the vehicle to be in the right entity with documented business use; many physicians claim it incorrectly
5. QBI deduction miscalculated — medicine is a Specified Service Trade or Business, but physicians below the phase-out threshold (and those who can get below it with retirement contributions) still qualify

The aggregate dollar impact of all five gaps at a $400,000 net income practice can reach $35,000–$60,000 per year — every year the structure remains uncorrected.

Go deeper:

• Why Is My Physician Practice Tax Bill So High?

7. What Should You Be Getting From Your CPA — and What Do Most Physicians Actually Get?

There is a significant gap in the physician practice CPA market between compliance-only service (accurate returns, filed on time) and full advisory service (proactive planning, quarterly projections, ongoing structure management). Most physician practices at $500K–$2M in revenue are in the former while paying prices that suggest they should be in the latter.

The test: can your current CPA answer these questions within 48 hours, right now, without scheduling a special consultation?

• What is my estimated tax liability for this year based on income to date?
• Am I on track with quarterly payments?
• What is my remaining retirement contribution room for this year?
• How much can I safely distribute from the practice this month?
• What strategies am I eligible for that we have not implemented?

A compliance engagement cannot answer most of these. An advisory engagement answers all of them as a matter of course.

Go deeper:

• How Much Does a CPA Cost for a Physician Practice?

What Does the Annual Tax Calendar Look Like for Physician Practice Owners?

The most common mistake: treating tax as a once-a-year event in March and April. Every date on this calendar represents a decision point. Missing it means either overpaying or carrying a penalty into the next year.

Where Should You Start?

If you are reading this guide and are not confident in your answers to the questions above, the highest-leverage first step is a review of your entity structure and S-corp salary — those two decisions affect every other number on the return.

From there: retirement contributions, quarterly payment calibration, and deduction capture. In that order. Each one compounds on the previous.

RTW.ai was built specifically for physician practices at $500K–$3M who need this level of active tax management without a $50,000/year full-advisory engagement. See how it works and what it costs.

Where Can You Find Tax Guides for Other Business Owners?

If you work with colleagues or partners outside healthcare:

• Professional Services Firm Owner Tax Guide — consultants, fractional executives, marketing agencies, staffing firms
• Contractor and Trades Business Tax Guide — general contractors, electricians, plumbers, HVAC, roofers