Single-member LLC taxes confuse nearly every solo founder at first — mostly because the LLC itself usually pays no income tax at all. Instead, profits "pass through" to you. Here is exactly how that works, what you will owe, and how to avoid the two mistakes that cost solo founders the most.

The core concept: pass-through taxation

By default, the IRS treats a single-member LLC as a "disregarded entity" — meaning for federal tax purposes, it pretends the LLC does not exist as separate from you. Your business profit or loss goes directly on your personal tax return (Schedule C), and you pay tax at your individual income tax rates.

Example: Your LLC nets $80,000 in profit. You report $80,000 of business income on your personal return. The LLC files no separate federal income tax return.

This is beautifully simple — one return, no corporate tax layer. But there is a catch, and it is a big one.

The self-employment tax surprise

On top of income tax, self-employed people pay self-employment tax: 15.3% covering Social Security (12.4% up to the annual wage base, ~$176,100 for 2026) and Medicare (2.9%, no cap, plus an extra 0.9% above $200k single/$250k joint).

On that $80,000 profit: roughly $11,300 in self-employment tax before you even get to income tax. Many first-year founders discover this in April and panic. Do not be them — plan for it from month one.

The 25–30% rule: set aside 25–30% of every dollar of profit in a separate savings account for taxes. When quarterly payments come due, the money is already there.

Quarterly estimated payments

Employees have taxes withheld from paychecks. You do not — so the IRS requires quarterly estimated tax payments (Form 1040-ES) if you expect to owe $1,000+ for the year. Deadlines: April 15, June 15, September 15, and January 15.

Miss them and you face underpayment penalties (currently around 8% annualized on the shortfall). The "safe harbor" rule: pay at least 100% of last year's total tax (110% if your income was over $150k) across the four quarters and you avoid penalties even if you underpay the current year.

Deductions: the good news

The tax code is generous to business owners. Common deductions for single-member LLCs:

  • Home office deduction — simplified method: $5/sq ft up to 300 sq ft ($1,500 max), no receipts needed.
  • Health insurance premiums — deductible if you are self-employed and not eligible for an employer plan.
  • Retirement contributions — SEP-IRA or Solo 401(k); a Solo 401(k) lets you contribute up to $69,000+ (2026 limits) as both employee and employer.
  • Business expenses — software, advertising, professional services, business travel, equipment (often fully deductible in year one via Section 179).
  • Qualified Business Income (QBI) deduction — up to 20% of qualified business income for eligible pass-through owners (phases out at higher incomes for service businesses).

Track everything from day one. A separate business bank account plus basic bookkeeping software makes tax season dramatically easier.

When to consider the S corp election

Remember the 15.3% self-employment tax applies to all your net profit as a default LLC. With an S corp election, you pay yourself a reasonable W-2 salary (subject to payroll tax) and take the rest as distributions free of self-employment tax.

The breakeven is typically around $60,000–$80,000 in consistent annual profit, after accounting for payroll service costs (~$30–60/month) and the extra tax return (Form 1120-S, often $500–$1,500 in accountant fees). Our LLC vs S corp guide has the full math with examples.

You do not need to decide at formation — file Form 2553 when your profits justify it.

State taxes: the forgotten layer

Federal is only half the story:

  • State income tax applies in most states (a few have none).
  • Franchise/minimum taxes: California's $800/year minimum is the infamous one, but several states have equivalents.
  • Sales tax: if you sell physical products, you likely need to collect and remit sales tax where you have nexus.
  • Local taxes: some cities (looking at you, NYC) layer on their own business taxes.

Two mistakes that cost real money

1. Not paying quarterly. The penalties and the April cash-flow shock are both avoidable. Set calendar reminders for the four deadlines.

2. Mixing personal and business money. Beyond the legal risk to your liability protection, commingled finances make bookkeeping a nightmare and cause missed deductions. Open the business account the week your LLC is approved.

Do you need an accountant?

For a simple single-member LLC with modest profit, good software plus diligence is enough. Hire a CPA when: profit approaches $60k+ (S corp analysis), you have employees, you operate in multiple states, or tax season starts causing anxiety. A one-hour consultation ($150–$300) before year-end often pays for itself many times over.

The bottom line

Single-member LLC taxation is simple in structure — profit passes to your personal return — but the 15.3% self-employment tax and quarterly payments catch founders off guard. Set aside 25–30% from day one, pay quarterly, deduct aggressively but honestly, and revisit the S corp question when profits grow. Taxes reward the organized.