An LLC is not a tax classification — it is a legal structure. The IRS lets you choose how the LLC is taxed. The default is pass-through (sole proprietorship for one owner, partnership for multiple). You can also elect S-Corp or C-Corp tax treatment. The choice can swing your tax bill by tens of thousands of dollars a year. This guide walks through each option with worked examples at $50k, $150k, and $500k of annual net profit.
Default: sole proprietorship (single-member LLC)
If you do nothing, a single-member LLC is treated as a "disregarded entity." Profits flow to your personal Form 1040 on Schedule C. You owe:
- Federal income tax at your marginal personal rate (10-37% in 2026)
- State income tax at your state's rate (0-13.3%)
- Self-employment (SE) tax of 15.3% on the first $176,100 of net earnings × 92.35%, then 2.9% Medicare on the rest, plus 0.9% additional Medicare for high earners
You can deduct half of the SE tax above the line. The QBI deduction (Section 199A) can reduce taxable income by up to 20% of qualified business income — subject to phase-outs starting around $197k single / $394k joint.
Default: partnership (multi-member LLC)
Multi-member LLCs file Form 1065 and issue K-1s to each member. Each member reports their share on their personal return and is subject to the same SE tax and QBI rules.
S-Corp election
By filing Form 2553, an LLC can be taxed as an S-Corporation. The LLC then pays the owner-employee a "reasonable salary" subject to payroll FICA (15.3%), and remaining profits pass through as distributions free of SE tax. This is the most popular tax optimization for profitable owner-operated businesses.
The catch:
- The "reasonable salary" must be defensible based on role, hours, and industry. Paying yourself $20k while taking $200k in distributions is an IRS audit magnet.
- Payroll, unemployment insurance, and an extra Form 1120-S return cost $1,500-$3,000/year.
- S-Corp election restricts ownership: only US citizens and residents, max 100 shareholders, one class of stock.
- Form 2553 must be filed within 2 months and 15 days of the start of the tax year you want it to apply.
C-Corp election
A C-Corp pays 21% federal corporate tax on profits. Distributions to owners as dividends are then taxed again at the personal level (0%, 15%, or 20% qualified dividend rates). This "double taxation" is why C-Corps are rarely chosen for owner-operated small businesses — but they make sense for businesses planning to reinvest heavily, raise VC funding, or eventually go public.
Worked example: $50,000 net profit
Single filer in Wyoming (no state income tax). Standard deduction $15,000.
- Pass-through: SE tax $7,065. Adjusted gross ~$46,468. Taxable income ~$31,468. Federal income tax ~$3,556. Total ~$10,621.
- S-Corp (salary $30k): FICA on $30k = $4,590. Federal income tax on $50k total ~$4,200. Total ~$8,790. Savings vs pass-through: ~$1,800.
- After payroll/admin costs of ~$1,500, S-Corp net advantage at $50k is marginal. Below this threshold, pass-through usually wins.
Worked example: $150,000 net profit
- Pass-through: SE tax ~$19,200. AGI ~$140k. Taxable income after standard deduction ~$125k. Federal income tax ~$22k. Total ~$41,200.
- S-Corp (salary $60k): FICA on $60k = $9,180. Federal income tax on $150k ~$25k. Total ~$34,200. Savings: ~$7,000.
- After payroll/admin: net advantage ~$5,500. S-Corp is clearly the better choice here.
Worked example: $500,000 net profit
- Pass-through: SE tax ~$26,800 (capped on Social Security portion). Federal income tax on remaining ~$140k. Total ~$170k.
- S-Corp (salary $150k): FICA on $150k ~$22,950. Federal income tax on $500k total ~$140k. Total ~$163k. Savings: ~$7,000.
- At this level, S-Corp savings come almost entirely from avoiding the 2.9% Medicare on the distribution portion ($350k × 2.9% = $10,150 saved). Worth it.
The QBI deduction in detail
Section 199A allows pass-through business owners to deduct up to 20% of qualified business income, subject to:
- Taxable income thresholds: 2026 ~$197,300 single / $394,600 MFJ.
- SSTB (specified service trade or business) phaseouts for doctors, lawyers, consultants, performing artists, and financial services — fully phased out above ~$247,300 single / $494,600 MFJ.
- W-2 wage and UBIA (unadjusted basis of qualified property) limits for non-SSTB businesses above the threshold.
The QBI deduction does not apply to S-Corp owner salaries (those are W-2 wages, not QBI). It does apply to the distribution portion. The interaction with S-Corp election is the main reason CPAs run multiple scenarios at year-end.
State tax: nexus matters more than formation state
A common myth: forming in a 0% state eliminates state tax. False. State income tax is owed where the LLC has economic nexus — typically where the owners reside and where business is conducted. A Wyoming LLC owned by a California resident, with the work performed in California, generally owes California state tax on the LLC's profits.
Quarterly estimated taxes
If you expect to owe more than $1,000 in federal tax, you must pay quarterly estimated taxes. Due dates: April 15, June 15, September 15, January 15. Penalties for underpayment are calculated at the IRS short-term rate + 3% (currently ~8% annualized). Use Form 1040-ES.