The Tax Surprise Problem
Every April, business owners discover they owe more than they expected. The profit felt real during the year, but they spent it. Now they're scrambling for cash or taking on debt to pay taxes.
The solution is simple: reserve money as you earn it. If you set aside 30-40% of every profit dollar, tax day becomes a non-event.
How Business Structure Affects Taxes
The IRS self-employment tax rate is 15.3% (12.4% Social Security + 2.9% Medicare). For 2026, the Social Security wage base is $184,500—income above this is only subject to the 2.9% Medicare portion.
- Sole Prop / Single-Member LLC: All profit flows to your personal return. You pay income tax plus 15.3% self-employment tax on everything.
- S-Corp: You pay yourself a salary (subject to payroll taxes), but profit distributions avoid self-employment tax. Saves money at higher profit levels.
- C-Corp: The corporation pays its own tax (21% federal). You only pay personal tax on what you take out as salary or dividends.
The Reserve Rule of Thumb
Most service business owners should reserve 30-40% of profit for taxes. If you're in a high-tax state or have high income, lean toward 40%. If you're in a no-income-tax state or have significant deductions, 30% may be enough.
The exact number matters less than the habit. It's better to over-reserve and get money back than to under-reserve and scramble.
Quarterly Estimated Taxes
If you expect to owe $1,000 or more in taxes, you're required to make quarterly estimated tax payments. Due dates are typically:
- Q1: April 15
- Q2: June 15
- Q3: September 15
- Q4: January 15 (of following year)
Missing these payments triggers penalties and interest. Your reserve account should fund these payments.
Note: This calculator provides estimates only. Tax situations vary significantly. Consult a tax professional for advice specific to your situation.
Sources
- IRS Self-Employment Tax Guide — Official SE tax rates and calculation
- IRS Estimated Taxes — Quarterly payment requirements and due dates
- Social Security Administration Wage Base — Annual contribution and benefit base amounts
- IRS Publication 505: Tax Withholding and Estimated Tax — Detailed guidance on tax payments
- IRS Business Structures Guide — Tax implications by entity type