What Percentage of Income Should a Small Business Owner Expect to Pay in Taxes?

First: Clearing Up the Confusion

When someone asks "what's my tax rate?", there are actually three different numbers they might be referring to — and confusing them leads to serious miscalculations:

• Marginal rate: The rate applied to your last dollar of income. If you're in the 22% federal bracket, your marginal rate is 22% — but you're only paying 22% on income above the bracket threshold, not on everything you earn.
• Effective rate: Your total federal income tax divided by your total taxable income. Because of the progressive bracket system, your effective rate is always lower than your marginal rate.
• Total tax burden: The complete picture — federal income tax + self-employment tax + NC state income tax. This is the number that actually matters for cash flow planning, and it's almost always higher than people expect.

This article focuses on the total tax burden — because that's what comes out of your bank account.

Self-Employment Tax: The One Most People Forget

Employees have Social Security and Medicare taxes split 50/50 with their employer — each pays 7.65%. Self-employed business owners pay both halves: 15.3% total.

• 12.4% for Social Security on net SE income up to $168,600 (2025 wage base)
• 2.9% for Medicare on all net SE income with no cap
• Additional 0.9% Medicare surtax on net SE income above $200,000 (single) or $250,000 (married filing jointly)

The one small offset: you can deduct half of your SE tax from your gross income before calculating income taxes. At $150,000 net SE income, that deduction is approximately $10,607. It helps, but it doesn't eliminate the SE tax burden.

Federal Income Tax Brackets 2025 (Brief Overview)

Federal income tax uses a progressive bracket system. For 2025, the brackets for single filers (business income is often reported on Schedule C as individual income) are approximately:

• 10% on taxable income up to $11,925
• 12% on income from $11,926 to $48,475
• 22% on income from $48,476 to $103,350
• 24% on income from $103,351 to $197,300
• 32% on income from $197,301 to $243,725
• 35% on income from $243,726 to $609,350
• 37% on income above $609,350

Married filing jointly thresholds are roughly double for most brackets. The marginal rate most small business owners think about is between 22% and 32% — but remember, this is on top of SE tax and NC state tax.

North Carolina State Income Tax

NC uses a flat income tax rate of 4.75% for 2025 on all taxable income regardless of amount. This simplicity is NC's advantage — there are no brackets to calculate. Starting in 2026, the rate drops to 4.5%, and the legislature has planned further reductions in subsequent years.

NC conforms to most federal deductions, so your business deductions that reduce your federal taxable income generally also reduce your NC taxable income. This means every deduction you find has a combined federal + NC value.

Combined Effective Tax Rates by Income Level

Here's what a typical NC sole proprietor with no employees and standard deductions pays in total taxes at various income levels. These are estimates — actual rates vary based on filing status, deductions, QBI eligibility, and other factors.

All figures are rough estimates for a single filer taking the standard deduction with no retirement contributions or other deductions. Actual tax liability will differ.

The QBI Deduction: A Significant Offset

The Qualified Business Income (QBI) deduction, created under the 2017 Tax Cuts and Jobs Act, allows eligible business owners to deduct up to 20% of their qualified business income from their taxable income. For a business owner in the 22% federal bracket with $100,000 QBI, this deduction is worth $4,400 in federal tax savings alone.

Key limitations:

• For income below approximately $197,300 (single) or $394,600 (MFJ) in 2025, most business owners can take the full 20% deduction
• Above those thresholds, "Specified Service Trade or Businesses" (SSTBs — which include accounting, law, consulting, financial services, and similar professional services) begin to phase out of eligibility
• The deduction reduces federal taxable income but does NOT reduce NC taxable income or SE tax

The S-Corp Effect

The most impactful structural change available to small business owners is the S-Corporation election. Here's why it matters for your tax rate:

As a sole proprietor or single-member LLC, you pay 15.3% SE tax on 100% of your net business income (up to the Social Security wage base). As an S-Corp, you split your business income into two parts: a reasonable W-2 salary (which is subject to payroll taxes) and a distribution (which is NOT subject to SE tax).

At $150,000 net income with a $75,000 salary:

• Sole proprietor SE tax: approximately $18,371 on the full $150,000
• S-Corp payroll taxes on $75,000 salary: approximately $11,475 (employee + employer portion)
• Tax savings from S-Corp structure: approximately $6,896 per year

At $150,000 net income, the S-Corp election typically reduces the effective total tax rate by 4–7 percentage points. At higher income levels, the savings increase further.

What Strategies Move the Needle Most

Ranked by impact for a typical NC small business owner earning $100K–$300K:

1. S-Corp election: 4–8 percentage point reduction in effective total rate at the right income level (typically $80K+ net income)
2. Retirement contributions (Solo 401(k) or SEP-IRA): 2–8 percentage point reduction depending on contribution amount and bracket
3. Home office deduction: modest but consistent annual savings ($1,500–$5,000 depending on space and expenses)
4. Vehicle and mileage deductions: $2,000–$15,000+ annually depending on usage and vehicle cost
5. NC PTET election (for S-Corps and partnerships): can effectively recover the $10,000 SALT cap limitation on federal returns