Payroll Tax vs. Income Tax: Understanding the Two Taxes on Every Dollar You Earn

Every dollar of business income faces up to two federal taxes: income tax and payroll tax (also called employment tax or self-employment tax). These are separate taxes with separate rates, separate bases, and separate rules. Income tax is the progressive tax (10-37%) that applies to all types of income (wages, business income, investment income, rental income). Payroll tax (FICA) is the flat tax (15.3% combined employer and employee share) that applies only to earned income (wages, salaries, and self-employment income). The distinction matters enormously for tax planning because strategies like the S-Corp election, retirement plan contributions, and the QBI deduction affect these two taxes differently. A business owner who understands both taxes can structure their compensation to minimize the total tax burden legally.

How do the two taxes interact by entity?

What are the penalties for late payroll tax deposits?

The IRS imposes graduated penalties for late payroll tax deposits: 2% if 1-5 days late, 5% if 6-15 days late, 10% if more than 15 days late, and 15% if still unpaid 10 days after the first IRS notice. These percentages apply to the unpaid deposit amount. The trust fund recovery penalty (IRC 6672) can hold owners, officers, and even bookkeepers personally liable for the employee’s share of unpaid payroll taxes, piercing the corporate veil entirely. This is one of the few tax penalties that cannot be discharged in bankruptcy.

How do I determine my payroll deposit schedule?

The IRS assigns businesses to either a monthly or semi-weekly deposit schedule based on the lookback period (the four quarters ending June 30 of the prior year). If total employment taxes during the lookback period were $50,000 or less, deposits are due monthly (by the 15th of the following month). Above $50,000, deposits follow a semi-weekly schedule (Wednesday/Friday based on payday). New businesses default to monthly. The schedule resets each calendar year. Regardless of schedule, accumulating $100,000 or more in undeposited taxes on any day triggers a next-business-day deposit requirement.

How do you calculate the self-employment tax deduction?

The self-employment tax is 15.3% of net self-employment earnings (12.4% Social Security on income up to the wage base of $176,100 for 2025, plus 2.9% Medicare on all earnings). Before calculating the tax, you multiply net earnings by 92.35% (0.9235) to account for the fact that employees only pay tax on wages after the employer’s share is excluded. You deduct half of the self-employment tax as an above-the-line deduction on Form 1040, which reduces your AGI but not your self-employment income for SE tax calculation purposes. The additional 0.9% Medicare surtax applies to self-employment income exceeding $200,000 for single filers or $250,000 for joint filers, and this additional tax is not eligible for the 50% deduction.

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.