Sole proprietor vs LLC vs S-Corp in 2025: which to choose

Summary

Sources: IRS.gov (Small Business & Self-Employed), Treasury.gov, SBA.gov — confirm rates and thresholds for your tax year.

Choosing among a sole proprietor (Schedule C), a disregarded single-member LLC, an S corporation, and sometimes a C corporation is not just about filing fees. It shapes exposure to self-employment (SE) tax, how you model the qualified business income (QBI) deduction, and how the IRS may scrutinize reasonable compensation for shareholder-employees.

1. Sole proprietor (Schedule C)

Net profit from the activity feeds SE tax on 92.35% of that amount, with the Social Security portion capped by the annual wage base and the Medicare portion continuing (with possible additional Medicare tax at higher income). This path is easy to explain to a new consultant but can be expensive when profit far exceeds a comparable reasonable wage.

Item	Teaching takeaway
SE tax	Shows up directly on business profit
QBI	May reduce federal income tax if eligible (real limits not fully modeled here)
State	Our demo defaults state tax to 0; use the slider to stress-test cash flow

2. Single-member LLC (disregarded)

By default, a one-owner LLC is disregarded for federal income tax: you often still report on Schedule C. Asset protection and contract design can still matter even when the federal calculation looks like a sole prop in our walkthrough.

3. S corporation

Reasonable compensation triggers payroll (FICA) compliance. Distributions avoid SE tax but remain ordinary income to the shareholder. IRS materials stress documented wages—review reasonable-compensation guidance before copying internet salary ratios.

4. When is C-Corp in the conversation?

The federal corporate rate (we use 21% as a teaching anchor) plus a second layer on qualified dividends can support retention or certain investor paths—at the cost of added complexity and double-tax awareness.

5. Illustrative numbers

Suppose $150,000 of net profit after deductions: on Schedule C, SE tax applies on the statutory base; with an S-Corp, part of the result may flow as wages (FICA) and part as distributions (no SE tax on the distribution itself, but ordinary income still applies). Always reconcile with a CPA who layers state tax, AMT, and other household income.

6. FAQ

Should I elect S-Corp from dollar one? Usually no—payroll costs and administration exist. Does QBI always apply? No—SSTB rules and W-2/unadjusted basis limits apply (not reproduced faithfully in this demo).

7. Official sources

• IRS — Small Business & Self-Employed
• SBA
• Treasury

8. Deeper checklist

Practical angles to document with a pro: (a) books and payroll records supporting S-Corp wages; (b) quarterly estimated tax coordination; (c) QBI interactions; (d) multistate remote-worker nexus; (e) year-end Section 179 timing; (f) separate LLC bank accounts; (g) lender covenants; (h) 1099-NEC flows; (i) certified payroll software; (j) annual IRS inflation updates to brackets and the standard deduction.

Re-read IRS instructions each filing year—inflation adjustments move brackets and thresholds. Use our simulator as a mental map, not a return.

Finally, write down assumptions: state rate, wage vs distribution split, QBI eligibility, other household income, credits, and estimated-tax cadence—clear notes speed up your CPA meeting.