Business Taxes 101: What Every Owner Should Know (2025)

Your entity choice drives everything

Before rates and forms, the biggest tax decision is how your business is structured. Sole proprietorships and partnerships are pass-through entities — profits flow to your personal return. S-corporations are also pass-through but can reduce self-employment tax. C-corporations pay their own 21% corporate tax. The IRS IRS — Business Taxes outlines the obligations for each.

The four kinds of business tax

The IRS — Small Businesses & Self-Employed groups business taxes into four buckets: income tax on profits, self-employment tax for owners, employment (payroll) taxes if you have staff, and excise taxes on specific goods or activities. Knowing which apply to you prevents nasty surprises.

Deductions and the QBI break

Ordinary business expenses reduce taxable profit, and many pass-through owners can also claim the Qualified Business Income (QBI) deduction of up to 20% of business income, subject to income limits and phase-outs. The IRS Publication 334, Tax Guide for Small Business details deductible expenses and recordkeeping expectations.

If you hire people

Employees mean withholding federal income tax, Social Security, and Medicare, paying the employer share, and filing payroll returns. Misclassifying workers as contractors to avoid this is a frequent audit trigger, so classify carefully and keep documentation.

Stay current and keep clean books

Separate business and personal finances from day one, reconcile monthly, and set aside for quarterly estimated payments. Clean books make tax time painless and are your best protection if the IRS ever asks questions.