Your business grew.
Your structure probably didn't.
Most solo service providers start as sole props because it's easy. Then income grows — and the SE tax bill grows with it. This page covers what you're actually paying, when to change it, and what to do before December 31.
Where are you in your business journey?
The problem
SE tax is 15.3%. And it compounds as you grow.
As a W-2 employee, you paid half of Social Security and Medicare — 7.65%. Your employer paid the other half. As a sole prop, you pay both sides. That's 15.3% on top of ordinary income tax.
It applies to your first $176,100in net earnings — so at $100,000 in profit, you're paying roughly $14,130 in SE tax before a dollar of income tax.
You can deduct half of it from your income. But you still pay all of it. And unlike income tax, there's no way to reduce it with retirement contributions or deductions — unless you change your entity structure.
Approximate SE tax only, before income tax. Figures use 2025 rates.
S-corp comparison calculator
Is an S-corp worth it at your income?
An S-corp doesn't eliminate SE tax — it limits it to just your W-2 salary. Profit beyond your salary comes out as distributions, which aren't subject to payroll taxes. The IRS requires the salary to be "reasonable compensation," so there's a floor, but the savings are real at the right income level.
Revenue minus business expenses — what's on Schedule C line 31
IRS requires "reasonable compensation" — typically 40–60% for service businesses. A CPA sets the defensible number.
Estimated S-corp compliance costs
California
Adds 1.5% S-corp net income tax (min $800)
SE tax now (sole prop)
$12,717
On $83,115 net earnings
Payroll tax as S-corp
$6,197
On $40,500 salary only
S-corp costs
Net annual savings
$3,820
$6,520 in SE tax savings minus $2,700 in compliance costs
Estimates only. S-corp FICA calculated on salary only; distributions avoid payroll tax. California 1.5% S-corp net income tax applied to gross profit as an approximation. Compliance costs are estimates — actual CPA and payroll fees vary. Does not account for QBI deduction, additional Medicare tax, or state income tax. Consult a CPA.
Beyond the S-corp question
Entity structure isn't the only lever. These moves are available to sole props and S-corps alike.
Solo 401(k) or SEP-IRA
A solo 401(k) lets you contribute up to $70,000 in 2025 — far more than an IRA. Contributions are deductible, which directly reduces your taxable income. For a $100k earner, maxing a Solo 401(k) can save $15,000+ in taxes.
Solo 401(k) vs SEP-IRA guideHome office deduction
If you work from a dedicated home office, you can deduct either $5/sq ft (simplified, max 300 sq ft) or your actual prorated home costs. Most solo operators who qualify don't take it.
Home office calculatorQualified business income (QBI) deduction
Pass-through income from a sole prop or S-corp may qualify for a 20% deduction under §199A — potentially eliminating tax on 20% of your net profit. Income limits and specified service trade rules apply.
How the QBI deduction worksSelf-employed health insurance deduction
If you pay your own health, dental, or vision premiums, 100% is deductible directly from income — not just as an itemized deduction. This reduces both income tax and, if structured correctly through an S-corp, SE tax as well. Most solo operators either miss it entirely or put it on the wrong line.
How the deduction worksTiming income and expenses
If you're near a tax bracket threshold, accelerating expenses into this year (prepaying software, buying equipment) or deferring December invoices to January can move meaningful dollars. This requires planning in October — not March.
Proactive planning guideFive mistakes solo operators make every year
Running everything through a personal bank account
Mixed accounts make bookkeeping a nightmare and invite IRS scrutiny. Open a dedicated business checking account before your next client payment. This isn't optional.
Not paying quarterly estimates
As a sole prop, no one withholds taxes for you. The IRS expects four payments per year — April, June, September, January. Miss them and you'll owe a penalty even if you pay in full by April.
Treating all revenue as available income
A third of your net profit belongs to the government. Set aside 25–35% of every client payment the moment it arrives. Put it in a separate savings account you don't touch.
Waiting to form an LLC until something goes wrong
An LLC creates a legal separation between your business debts and personal assets. It doesn't cost much. A lawsuit without one can cost everything.
Never revisiting the S-corp question as income grows
At $50k in profit, an S-corp probably doesn't pencil out. At $100k+, it almost always does. The SE tax savings grow with your income — and most solo operators never run the numbers.
Cash management
Don't wait until April to figure out the tax money
The simplest system that works: every time a client pays you, move a fixed percentage to a dedicated tax savings account the same day. The Profit First method uses three accounts — operating, tax reserve, and profit — so you always know exactly what's available to spend.
More tools
Entity Structure Analyzer
Compare sole prop, LLC, and S-corp at your profit level
OpenS-Corp Salary Calculator
Find a defensible W-2 salary before setting payroll
OpenPer-Payment Tax Reserve
How much to move to your tax account every time you get paid
OpenQuarterly Estimate Planner
Build a payment schedule you'll actually follow
OpenSE Tax Calculator
See exactly what SE tax costs you and when the S-corp math works
OpenRelated reading
Self-Employment Tax Explained
SE tax is 15.3% on top of income tax — how it's calculated, what the deductible half saves, and why the S-corp election is the primary way to reduce it.
ReadLLC vs S-Corp: Which Structure Is Right for You?
The difference between the legal structure and the tax election, when the S-corp saves money, and what it actually costs to run one.
ReadIndependent Contractor Taxes: What You Owe
Going from W-2 to 1099 — what the full tax bill looks like and the three moves that reduce it most.
ReadCommon questions
I've been a sole prop for years and never set up an LLC. Is it too late?+
It's not too late. You can form an LLC at any point — the filing takes a day. The protection is prospective (it doesn't cover past activities), and for California owners there's the $800 annual franchise tax to factor in, but for most active businesses the liability protection is worth it.
If I elect S-corp, do I have to do payroll myself?+
No — and you shouldn't. Use a payroll service like Gusto or Rippling ($50–120/month) that handles federal and state deposits, W-2 filings, and the quarterly 941s automatically. Trying to manage payroll deposits manually is how owners trigger penalties.
What's a 'reasonable' salary for a personal trainer or therapist?+
The IRS looks at what you'd pay someone else to do your job. For a licensed therapist at $150k in revenue, that might be $65–75k. For a personal trainer at $80k, maybe $40–50k. The right number depends on your specific work, hours, and industry benchmarks. A CPA sets the defensible number — not a formula.
I was told I should be a sole prop for the QBI deduction. Is that true?+
Partially. The QBI deduction under §199A applies to both sole props and S-corps — it's not exclusive to sole props. For income below the threshold (~$197k single, ~$394k MFJ), QBI works for both structures. Above that threshold, specified service trades face phase-outs regardless of entity type.
Can I switch to an S-corp mid-year?+
Yes, with conditions. If you haven't already formed the entity, you'd form an LLC (or corporation) and file Form 2553 within 75 days of formation. If you're already past that window for the current year, you can elect S-corp status starting January 1 of next year by filing by March 15.
Work with Matt
Ready to build a plan?
You've built a real business. Your tax structure should reflect that. SE tax savings, retirement contributions, quarterly planning — these move the number before April.
Tax services provided through Matt Reese, CPA. This page is educational and does not constitute tax or investment advice.