Solo Founder Tax Planning: SE Tax, S-Corp, and the $80k Threshold

The U.S. tax structure for solo founders treats the same dollar of business income very differently depending on how the business is organized. A founder netting $120,000 as a default LLC pays a structurally different tax bill than the same founder, with the same revenue and expenses, electing S-corp status. The gap is large enough to matter and small enough to be wiped out by the wrong decision at the wrong income level.

This piece covers what SE tax is, how the S-corp election changes the math, where the break-even threshold actually sits, and the second-order effects (state tax, payroll cost, audit risk) that move the number for individual founders. It is not tax advice. The IRS publications cited^[1][3] and a CPA who has run the math on your specific state are the authoritative sources.

What self-employment tax actually is

Self-employment tax is the combined Social Security and Medicare contribution that W-2 employees split with their employer. The W-2 employee pays 7.65% (6.2% Social Security + 1.45% Medicare) and the employer pays a matching 7.65%. A self-employed person pays both halves, which is the 15.3% rate.

The 2024 mechanics:

• Social Security portion: 12.4% on net earnings up to $168,600 (the wage base, adjusted annually).
• Medicare portion: 2.9% on all net earnings, no cap.
• Additional Medicare: 0.9% on net earnings above $200,000 single filer / $250,000 joint.
• Half of SE tax is deductible above-the-line on Form 1040, which softens the effective rate to roughly 14.1% on the SS portion and 2.7% on the Medicare portion at typical marginal income tax rates.

SE tax sits separately from federal and state income tax. A founder at $100,000 net Schedule C income pays SE tax (~$14,130 after the half-deduction adjustment), then pays federal income tax on the rest, then pays state income tax on the rest. SE tax is the line that surprises first-time solo founders coming from W-2 employment, where the employer-paid half is invisible.

Default LLC: SE tax on every dollar

A single-member LLC with no tax election is a "disregarded entity" for federal purposes. All net income flows to the founder's Schedule C and the entire net is subject to SE tax. There is no salary distinction, no distributions, just one line of net business income.

For a founder at $80,000 net income, the math:

SE tax = $80,000 × 0.9235 × 0.153 = $11,304

(The 0.9235 multiplier converts net business income to "net earnings from self-employment," which is the actual SE-tax base. The IRS uses this factor to roughly equate the self-employed taxpayer to the W-2 baseline after the employer-side FICA is removed from wages.)

Half of that ($5,652) is deductible above-the-line for income tax purposes, recovering roughly $1,300 to $1,800 depending on marginal rate. The net SE-tax cost is around $9,500 to $10,000 on $80,000 of business income, which is 11.9 to 12.5% of the gross.

Default LLC has three real advantages: zero compliance cost beyond the personal return, no payroll system, no separate corporate tax filing. For founders at low net income, those advantages outweigh the SE-tax inefficiency.

The S-corp election and reasonable salary

The S-corp election (Form 2553) reclassifies an LLC or corporation for tax purposes. Income flows through to the owner's personal return (similar to default LLC), but the structure introduces a salary/distribution split:

• Reasonable salary: the portion the owner pays themselves as a W-2 wage, subject to full payroll taxes (FICA, FUTA, state unemployment).
• Distributions: additional profit drawn from the business, subject to ordinary income tax but NOT to SE tax / FICA.

The IRS rule is that reasonable salary must reflect what the same work would command on the open market^[3]. A solo founder running a software business cannot pay themselves $20,000 salary and take $200,000 in distributions; the IRS has audited and reclassified low-salary cases for decades. The widely-used safe harbor is roughly 40 to 60% of net business income as salary, with the exact ratio depending on industry, role, and BEA wage data for comparable W-2 positions^[5].

Worked illustration. A solo SaaS founder with $200,000 net business income pays $90,000 reasonable salary and takes $110,000 in distributions. Tax outcome:

• Salary FICA: $90,000 × 0.153 = $13,770 (split nominally between owner and corporation, but the owner bears both as the only shareholder).
• Distribution FICA: $0 on $110,000.
• Compare to default LLC: $200,000 × 0.9235 × 0.153 = $28,259 SE tax (capped portion: only the first $168,600 hits SS, so the actual figure is $25,693 + the Medicare on the excess), so call it ~$26,000 SE tax in default LLC vs $13,770 FICA in S-corp.

S-corp savings on this scenario: roughly $12,000 in payroll-tax savings, before the cost of S-corp compliance.

The $80k threshold (and why it isn't a fixed number)

The crossover where S-corp savings start to exceed S-corp overhead depends on three founder-specific numbers:

• Net business income. The higher, the more SE tax savings the S-corp generates per dollar of distribution.
• Reasonable salary ratio. A founder in a category with lower BEA wage benchmarks (light technical solo work) can defensibly take a 40% salary ratio, generating more distribution and more savings. A founder in a senior-engineer-equivalent role faces a 50 to 60% ratio.
• S-corp overhead. Payroll service ($600 to $1,500/year), additional accounting and S-corp tax return ($800 to $2,500/year), state-level S-corp fees (Massachusetts: $456 minimum; California: $800 minimum franchise tax, plus 1.5% S-corp tax on net income; New York: $25 to several hundred). Total annual overhead: $1,500 to $4,000 depending on state and service tier.

Approximate break-even table (federal only, assuming 50% reasonable salary ratio, $2,500 S-corp overhead):

Net biz income   Default LLC SE   S-corp FICA   Saving   Net of overhead
  $50,000          $7,065           $3,825        $3,240   $740
  $70,000          $9,891           $5,355        $4,536   $2,036
  $80,000          $11,304          $6,120        $5,184   $2,684
  $100,000         $14,130          $7,650        $6,480   $3,980
  $150,000         $19,887          $11,475       $8,412   $5,912
  $200,000         $24,200 (SS cap) $13,770       $10,430  $7,930

The crossover at the assumed 50% salary ratio and $2,500 overhead lands around $50,000 to $60,000 of net income for marginal viability and $80,000+ for clear material savings. Below $50,000, S-corp overhead eats the savings. Between $50,000 and $80,000, savings exist but the complexity is rarely worth it for a first-year solo founder. Above $80,000, the math becomes lopsided in favor of the election.

Why the threshold is not fixed: California adds a 1.5% S-corp tax that pushes the crossover up to roughly $100,000 net income. A founder paying a CPA $5,000 instead of $1,500 sees the threshold jump to $110,000+. A founder in a state with no income tax (Texas, Florida, Washington) and a flat $800 LLC fee sees a clean threshold around $65,000 to $75,000.

Run your own numbers with the Profit Margin Calculator to identify net business income before tax planning. The margin calculation is the input to the SE-tax calculation; both have to be defensible before the S-corp decision is sound.

Worked example at three income levels

Same founder, same business (US-based solo SaaS, single-member entity), three income levels, comparing default LLC and S-corp election with realistic state and overhead assumptions. Texas-based founder, $1,800 payroll service, $2,200 CPA cost for S-corp return, 50% reasonable salary ratio.

SCENARIO A: $60,000 net business income (year 1)
  Default LLC:
    SE tax (after half-deduction recovery)    $7,820
    Federal income tax (single, std deduction) $5,940
    Total federal                             $13,760

  S-corp election:
    Salary $30,000, distribution $30,000
    FICA on salary                            $4,590
    Federal income tax                        $5,720
    Payroll + CPA overhead                    $4,000
    Total federal + overhead                  $14,310

  Verdict: default LLC wins by $550. S-corp not yet worth it.

SCENARIO B: $100,000 net business income (year 2)
  Default LLC:
    SE tax (after half-deduction recovery)    $12,560
    Federal income tax                        $14,360
    Total federal                             $26,920

  S-corp election:
    Salary $50,000, distribution $50,000
    FICA on salary                            $7,650
    Federal income tax                        $13,640
    Payroll + CPA overhead                    $4,000
    Total federal + overhead                  $25,290

  Verdict: S-corp wins by $1,630.

SCENARIO C: $200,000 net business income (year 3)
  Default LLC:
    SE tax (after half-deduction recovery + SS cap) $22,650
    Federal income tax                        $40,200
    Total federal                             $62,850

  S-corp election:
    Salary $90,000, distribution $110,000
    FICA on salary                            $13,770
    Federal income tax                        $39,200
    Payroll + CPA overhead                    $4,000
    Total federal + overhead                  $56,970

  Verdict: S-corp wins by $5,880.

The pattern is consistent across all the founder configurations the IRS publications cover^[1][2]: at low income, default LLC wins on simplicity. Around the $80k inflection, S-corp savings start exceeding the overhead. At $150k+, the S-corp savings become a material portion of the founder's effective tax rate.

S-corp costs: payroll, accounting, complexity

The financial overhead is only part of what the election adds:

• Payroll service. Gusto, ADP RUN, Square Payroll, or equivalent. Solo founders pay $40 to $80/month. The service handles federal and state withholding deposits, quarterly 941s, annual W-2, and the state unemployment registrations that vary by state.
• S-corp tax return (Form 1120-S). A CPA charges $800 to $2,500 to prepare an 1120-S and the K-1 that flows to the personal return^[4]. DIY is technically possible but the IRS audit rate on S-corp returns prepared without professional review is materially higher.
• Reasonable compensation documentation. The IRS expects a defensible justification for the salary ratio. Most CPAs use BEA industry wage data^[5] and a memo to file. This is a 30-minute exercise the first year and should be revisited annually.
• State complexity. California's 1.5% franchise tax, Tennessee's franchise and excise tax, New York City's general corporation tax, Illinois's replacement tax. Each adds a layer that the federal-only break-even table misses. A founder in a high-tax state should run state-specific numbers before electing.
• Cash-flow timing. Payroll runs require cash in the operating account on payroll dates, which is a different cash-management pattern than the lumpy quarterly estimated tax payments of default LLC.

Edge cases and second-order effects

• Solo 401(k) contribution math changes. Default LLC: contribution base is net SE income minus half of SE tax. S-corp: contribution base is W-2 salary. A founder paying a low salary to maximize FICA savings reduces their own retirement-contribution ceiling. The optimal salary often lands above the FICA-minimization point because of the 401(k) base.
• QBI deduction interaction. Section 199A allows a 20% deduction on qualified business income for pass-through entities, including S-corps and default LLCs. The deduction phases out at higher incomes for "specified service trades and businesses" (most consulting). The interaction with S-corp salary is non-trivial: paying yourself more salary reduces QBI base, which reduces the deduction. Optimal salary is a joint optimization of FICA savings and QBI preservation.
• Health insurance. S-corp shareholder health insurance must be added to W-2 wages for the 2% owner, which sounds like a tax hit but recovers on the personal return as a self-employed health insurance deduction. Net is usually neutral, but the paperwork is non-trivial.
• State residency changes mid-year. A founder relocating from California to Texas mid-year creates a multi-state S-corp filing situation that costs more in CPA fees than the relocation might save in the first year. Plan around it; surprise it and burn $1,500+.
• Reasonable comp audit risk. The IRS publishes case data showing it pursues reasonable-compensation cases when salary is set below 25% of distributions. A 40 to 50% ratio is the practical lower bound for solo SaaS founders without inviting scrutiny.

Common founder tax mistakes

• Electing S-corp too early. A first-year founder netting $30,000 who elects S-corp pays roughly $4,000 in overhead to save $1,500 in SE tax. Net loss of $2,500. The election can be filed mid-year (Form 2553) or revoked, but the year of error is unrecoverable.
• Setting salary too low. The temptation is to minimize FICA by paying $10,000 salary and taking $90,000 distribution. The IRS reclassification risk plus penalty plus interest typically exceeds the original FICA savings 3 to 5x in audited cases.
• Forgetting state-level S-corp taxes. California's 1.5% on net income wipes out the federal savings for many solo founders below $150k net. Always run the state column.
• Not separating personal and business expenses cleanly. Both default LLC and S-corp require the founder to maintain a clean business-expense trail. Schedule C audit defense and S-corp audit defense both depend on the same fundamentals: receipts, mileage logs, business-purpose documentation.
• DIY S-corp returns. Form 1120-S has more lines and more interaction with state-level forms than founders typically expect. A $1,800 CPA fee is cheap insurance against a $5,000 amendment.
• Skipping the quarterly estimated tax payments. Both structures require quarterly estimates. The penalty for underpayment is small but real (~7 to 8% annualized in 2024). The fix is one calendar reminder.

The S-corp decision is not a permanent commitment. Founders revoke and re-elect as income changes, business structure shifts, or state residency changes. The honest math is the same every year: net business income, reasonable salary at industry-defensible ratio, overhead cost in your specific state and CPA tier, run the table, decide. The break-even threshold for most solo founders sits in the $70,000 to $90,000 net-income band, and that is the income level at which the conversation with a CPA stops being optional.