Somewhere in your feed right now, a physician with a ring light is explaining that an S corporation will save you $20,000 a year. The arithmetic behind that claim assumes a full-time surgeon can defensibly pay herself a $100,000 salary, and it collapses on contact with the IRS position that has stood since 1974. The honest version is smaller and more conditional: for most physicians, an S corporation election saves a few thousand dollars a year in Medicare tax, costs one to five thousand in overhead, interacts badly with the QBI deduction below the income thresholds, and occasionally makes sense anyway. This article works the real numbers at $400,000 of 1099 income so you can see exactly where the savings come from, why they are capped, and who is left over once the arithmetic is honest.
Before the entity question, make sure the foundation is set — the moonlighting income module and the 1099 starter kit cover the deductions, estimated taxes, and retirement accounts that matter at every income level. The S corporation is the last optimization, not the first.
The election changes one tax, and it is not income tax
An S corporation election (Form 2553; the underlying entity is usually the PLLC or professional corporation your state requires anyway) does not reduce federal income tax by a single dollar. Every dollar of profit still lands on your 1040 at ordinary rates, salary and distribution alike. What the election changes is employment tax — and only on the slice of profit you take as distributions rather than salary.
As a sole proprietor, your entire net profit runs through self-employment tax: 15.3 percent (12.4 percent Social Security plus 2.9 percent Medicare) on 92.35 percent of net earnings up to the Social Security wage base — $184,500 in 2026 per the Social Security Administration — then 2.9 percent Medicare with no cap, plus the 0.9 percent Additional Medicare Tax above $200,000 of earnings ($250,000 married filing jointly). As an S corporation owner, only your W-2 salary carries those taxes; distributions carry none.
Key insight
At physician incomes, the Social Security portion is a red herring. Any defensible full-time physician salary exceeds the $184,500 wage base, so the 12.4 percent tax is paid in full under either structure. The entire real prize is Medicare tax on the distribution slice: 2.9 percent, plus 0.9 percent above the threshold — 3.8 cents per distributed dollar, at most. Every claimed saving larger than that is assuming a salary below the wage base, which is where the IRS problem begins.
Reasonable compensation: when the physician is the service, the income is salary
The IRS position dates to Rev. Rul. 74-44: shareholder-employees who take distributions in place of salary for services they actually performed get those distributions reclassified as wages, with back employment taxes and penalties. Fact Sheet FS-2008-25 and the S corporation audit guidance list the factors — training and experience, duties and responsibilities, time devoted, and what comparable businesses pay for comparable services — and the courts have backed reclassification, most notably in David E. Watson, P.C. v. United States (8th Cir. 2012), where an accountant paying himself $24,000 against roughly $200,000 of firm profit lost.
For physicians the doctrine bites unusually hard, because in a solo 1099 practice the shareholder is not merely managing the business — the shareholder is the service. When every dollar of collections traces to your own hands, license, and call schedule, the defensible position is that most of the profit is compensation for those services. Published compensation surveys — 2026 medians for most specialties sit above $300,000 — are exactly the comparables an examiner reaches for. A locums intensivist grossing $400,000 who pays herself $120,000 is not aggressive; she is indefensible.
Important
Reasonable compensation is not a number you choose; it is a number you must be able to defend with documentation — survey data for your specialty, hours worked, wRVU or shift benchmarks. Set the salary first from the evidence, and let the distribution be whatever remains. Advisers who start from the desired tax saving and back into the salary are writing your audit exposure, not your plan.
The worked example: $400,000 of 1099 income, realistic salary, real savings
Example calculation
Assumptions, stated explicitly: hospitalist, married filing jointly, $400,000 net 1099 profit after expenses; 2026 wage base $184,500; Additional Medicare Tax threshold $250,000 MFJ; salary set at $300,000, defensible against specialty survey medians; combined employer-plus-employee payroll tax shown so the comparison is like for like; income tax ignored because the election does not change it.
Sole proprietor. Social Security: 12.4% × $184,500 = $22,878. Medicare: 2.9% × ($400,000 × 92.35% = $369,400) = $10,713. Additional Medicare: 0.9% × ($369,400 − $250,000) = $1,075. Total: $34,666.
S corporation, $300,000 salary, $100,000 available as distributions. Social Security: 12.4% × $184,500 = $22,878 (identical — the salary exceeds the wage base). Medicare: 2.9% × $300,000 = $8,700. Additional Medicare: 0.9% × ($300,000 − $250,000) = $450. Total: $32,028.
Gross employment-tax saving: $34,666 − $32,028 = $2,638 per year. The deduction offsets (half of SE tax for the sole proprietor, the employer payroll share for the S corporation) approximately cancel, leaving the net figure near $2,600. Push the salary to $250,000 — still defensible for some specialties and schedules — and the saving grows to roughly $4,500. That is the honest range at $400,000: about $2,600 to $4,500 a year, before costs.
Where does the ring-light $20,000 come from? Set the salary at $120,000 in the same example and the arithmetic mechanically produces roughly $15,000 to $19,000 of savings — most of it dodged Social Security tax below the wage base — attached to a compensation figure no full-time physician can document. The savings are only as real as the salary is defensible, and for a physician whose own services generate the income, the defensible salary consumes most of the profit.
The costs nobody posts: payroll, filings, franchise tax, retirement space
The S corporation is not free to operate, and the costs recur every year the savings do.
| Annual cost | Typical range |
|---|---|
| Payroll service (required — you must run W-2 payroll on yourself) | $500–$1,200 |
| Separate S corporation return (Form 1120-S) preparation | $800–$2,500 |
| State entity-level taxes | $0 to several thousand — some states tax S corporation income directly (California levies 1.5 percent of net income with an $800 minimum; New York City does not recognize the election at all) |
| Annual report, registered agent, bookkeeping formality | $100–$500 |
Against a $2,600–$4,500 gross saving, a realistic $1,500–$4,000 cost stack means the election is frequently a break-even proposition at $400,000 — and in a franchise-tax state it can be negative.
There is also a quieter cost inside your retirement plan. A solo employer contribution is capped at 25 percent of W-2 salary for an S corporation owner. At a $300,000 salary the $72,000 overall limit (Notice 2025-67) is still reachable, but the low-salary strategies that generate the advertised tax savings destroy contribution room: at a $120,000 salary, the employer piece caps at $30,000 and the total plan tops out at $54,500 — $17,500 of forfeited, which at high marginal rates can be worth more than the payroll-tax saving itself. The legitimate tax-reduction hierarchy ranks retirement-plan space above entity engineering for exactly this reason.
Two administrative wrinkles deserve a sentence each. Health insurance premiums for a more-than-2-percent shareholder must run through payroll — included in box 1 of your own W-2, then deducted on your 1040 as self-employed health insurance — and skipping that payroll step puts the deduction at risk; sole proprietors simply deduct the premiums with no choreography. And when a salary is set below the wage base, part of the payroll-tax saving quietly comes back as reduced future Social Security benefits, because benefits are computed from taxed earnings. At defensible physician salaries this is moot — one more sign the low-salary playbook was never designed for physicians.
One genuine convenience runs the other way. Payroll withholding replaces most of your quarterly estimated-payment burden, and withholding is treated as paid evenly through the year regardless of when it actually happens — so a physician who underpaid through September can cure the shortfall with heavy withholding on a December payroll run, an option quarterly estimates do not offer. It is a real administrative benefit; it is not a tax saving, and it does not belong in the savings column of anyone's projection.
The QBI interaction: salary you pay yourself is deduction you cannot take
Section 199A adds a second penalty for electing too early. Your own W-2 salary from the S corporation is excluded from qualified business income, so every dollar you move from profit to salary shrinks the base of the 20 percent deduction — and reasonable-compensation rules force that move. At $400,000 with high joint taxable income, the SSTB phase-out has often eliminated the deduction anyway, and the interaction is moot. Below the 2026 thresholds ($201,750 single, $403,500 married filing jointly per Rev. Proc. 2025-32), it is decisive.
Example calculation
Assumptions, stated explicitly: resident moonlighter, single, $80,000 net 1099 profit, taxable income far below $201,750, 22 percent bracket.
As a sole proprietor: QBI = $80,000 − $5,652 (deductible half of SE tax) = $74,348; deduction = 20% × $74,348 = $14,870. As an S corporation with a $60,000 salary: QBI is roughly the $20,000 remainder minus payroll costs; deduction is about $4,000. Deduction lost: roughly $10,900, costing about $2,400 of income tax at 22 percent. Medicare tax saved on the $20,000 distribution: 2.9% × $20,000 = $580. Net effect of the election: roughly $1,800 worse per year, before paying for payroll and the 1120-S.
For a physician under the QBI thresholds, the election usually costs more in lost Section 199A deduction than it saves in Medicare tax. It grows more attractive as income rises past the phase-out — exactly the range where reasonable compensation caps how much can be distributed.
Who the election actually fits
Strip away the broken assumptions and a genuine, smaller use case remains. The election tends to pencil when several of these hold at once: 1099 profit comfortably above what a documented reasonable salary requires — commonly $500,000 and up, or income with real non-personal-service components such as employed clinicians, ancillary service lines, or facility revenue, where profit legitimately exceeds your own compensation; a state with no entity-level tax on S corporations; taxable income already past the QBI phase-out, so no deduction is being sacrificed; a salary set high enough to preserve the full $72,000 of defined-contribution space; and enough tolerance for administration to run payroll, file the 1120-S, and keep corporate formalities every single year. A dermatologist who owns a practice with two associates and an aesthetics line netting $900,000 fits. A locums hospitalist netting $350,000 almost never does.
Quick takeaway
Run the decision in this order: establish the defensible salary for your specialty first, compute 3.8 percent of what remains, subtract your state's entity costs and any lost QBI deduction, and only then decide. If the honest answer is a net saving under about $3,000, the recurring complexity is rarely worth it — and the analysis should be rerun whenever income, state, or thresholds change.
Common questions
Is an LLC the same thing as an S corporation?
No. The LLC (or professional corporation, in states that require one for physicians) is the legal entity; the S corporation is a tax election that entity files on Form 2553. A single-member PLLC that makes no election is taxed exactly like a sole proprietorship — same Schedule C, same SE tax. Forming an LLC changes nothing about employment tax by itself.
Does an S corporation protect me from malpractice liability?
No. No entity shields you from liability for your own professional negligence; that is what malpractice coverage is for. The entity can help with non-clinical liabilities and with the acts of employees, but a physician with an S corporation is exactly as responsible for her own care as a physician without one.
Can I elect S status partway through the year, or retroactively?
Form 2553 is generally due within two months and fifteen days of the start of the tax year the election covers, and the IRS grants late-election relief liberally under Rev. Proc. 2013-30 when the failure was inadvertent. The practical constraint is payroll: a retroactive election means retroactively reasonable W-2 wages, which gets messy after the fact. Decide before the year starts, not in November.
My accountant says I will save five figures. Who is wrong?
Ask one question: what salary does the projection assume, and what survey documents it? If the assumed salary is below what your specialty's data supports — or below the $184,500 wage base for full-time clinical work — the projection is monetizing audit risk, not tax law. A projection built on a defensible salary at physician income levels almost always lands in the low single-digit thousands.
What to do next
- Pull your specialty's compensation survey data and write down the salary you could defend in an audit tomorrow. This number, not the tax saving, is the foundation of the whole analysis.
- Compute the honest saving: roughly 3.8 percent of profit above that salary, using the calculation pattern above with your own numbers.
- Subtract the recurring costs for your state — payroll service, 1120-S preparation, and any entity-level tax.
- Check the QBI side: if your taxable income is below $403,500 married filing jointly ($201,750 single), quantify the Section 199A deduction the salary requirement would destroy.
- Confirm your retirement plan survives: at your defensible salary, verify the solo 401(k) still reaches the contribution level you want before electing.
- If the net is still positive by a margin that pays for the complexity, have a physician-literate CPA file Form 2553 prospectively for the coming January — not retroactively for the current year.
The S corporation is a modest tool that social media promoted into a miracle; the arithmetic above is the whole decision, and it works with or without us. This is education, not individualized financial advice.