Small Business & Self-Employment Tax Basics

When you work for an employer, your FICA taxes — Social Security (6.2%) and Medicare (1.45%) — are split evenly between you and your employer. When you're self-employed, you are both the employee and the employer, so you pay both halves: 12.4% for Social Security and 2.9% for Medicare, for a combined self-employment (SE) tax rate of 15.3% on net self-employment earnings. This is calculated on IRS Schedule SE and flows onto your Form 1040.

SE tax applies to net self-employment earnings — generally, your business revenue minus ordinary and necessary business expenses. Net SE income of $400 or more in a year triggers the requirement to file Schedule SE and pay SE tax. The Social Security portion applies only up to an annual wage base (which adjusts each year); the Medicare portion applies to all net SE income, with an additional 0.9% on earnings above $200,000 for single filers ($250,000 for married filing jointly) under the Additional Medicare Tax.

The IRS allows you to deduct half of your SE tax as an adjustment to income on Form 1040 (Schedule 1). This deduction reduces your adjusted gross income, which in turn lowers your regular income tax — even if you don't itemize deductions. It exists because employed workers pay only their half of FICA; allowing self-employed workers to deduct the employer-equivalent half creates parity. See IRS Publication 334 (Tax Guide for Small Business) for full details.

Estimated taxes are quarterly payments to the IRS for income not covered by payroll withholding — self-employed workers, freelancers, landlords, and investors typically need to make them. The IRS outlines the calculation process in Form 1040-ES and its accompanying worksheet. There are two main approaches: project your actual current-year liability, or use the safe harbor rule to guarantee penalty avoidance regardless of what you earn.

The safe harbor rule lets you avoid the underpayment penalty entirely by basing your payments on last year's tax liability rather than this year's projected income. Pay 100% of your prior-year federal tax in four equal installments (or 110% if your prior-year adjusted gross income exceeded $150,000). The main advantage: once you've paid the safe harbor amount, you're penalty-free even if your income is much higher this year. The main disadvantage: if income drops, you'll overpay and wait for a refund at filing.

• Step 1: Estimate your total gross income for the year — wages, self-employment revenue, rental income, investment income, and any other taxable sources.
• Step 2: Subtract expected above-the-line deductions (retirement contributions, HSA, SE tax deduction) to get estimated AGI, then subtract the standard deduction (or estimated itemized deductions) and any qualified business income (QBI) deduction.
• Step 3: Apply the tax brackets to the resulting taxable income to estimate your federal income tax. Include self-employment tax (15.3% on net SE earnings, calculated on Schedule SE) separately.
• Step 4: Subtract any expected tax credits (child tax credit, education credits, etc.) to get estimated total tax liability.
• Step 5: Subtract any W-2 withholding for the year. Divide the remainder by 4 — that's each quarterly payment.
• Reforecast each quarter if income changes significantly — especially for seasonal businesses.

These two rates describe different things about how much tax you pay — and confusing them leads to one of the most common tax misconceptions: the idea that earning more money can somehow leave you with less after-tax income because a higher bracket 'kicks in.' That's not how progressive taxation works.

Your marginal rate is the rate imposed on the last (highest) portion of your income — the bracket you've reached. The U.S. federal income tax system has seven brackets: 10%, 12%, 22%, 24%, 32%, 35%, and 37%. If your taxable income lands in the 22% bracket, your marginal rate is 22% — but that rate only applies to income within that bracket's range, not to every dollar you earned. Lower portions of income are still taxed at 10% and 12%.

Your effective rate is simple: total federal income tax paid ÷ total taxable income. If you paid $8,000 in federal income tax on $50,000 of taxable income, your effective rate is 16%. This blended rate — the weighted average of all brackets applied to your income — will always be lower than your marginal rate (unless all your income falls in the bottom bracket).

The IRS allows businesses to deduct expenses that are "ordinary and necessary" for carrying on a trade or business — the foundational rule in IRS Publication 535 (Business Expenses). An ordinary expense is common and accepted in your industry; a necessary expense is helpful and appropriate (not luxury or personal). Every dollar of legitimate deductions reduces your net taxable income and, by extension, your tax bill.

The IRS covers a wide range in Pub 535 and Pub 334 (Tax Guide for Small Business):

• Rent or lease payments for office, retail, or warehouse space.
• Wages, salaries, and benefits paid to employees.
• Interest on business loans and lines of credit.
• Office supplies, software subscriptions, and utilities.
• Professional services: legal, accounting, consulting fees.
• Business insurance premiums.
• Depreciation on business equipment, vehicles, and property.
• Marketing and advertising costs.

"Tax write-off" and "tax deduction" mean the same thing. The IRS foundational rule is in Publication 535 (Business Expenses): to be deductible, an expense must be ordinary (common and accepted in your industry) and necessary (helpful and appropriate for your business). Every qualifying write-off reduces your net taxable income — and by extension, your tax bill. This is educational content; consult a CPA or tax professional for your specific situation.

• Rent and utilities — office, retail, or warehouse space used for business.
• Payroll and benefits — wages, salaries, health insurance premiums paid for employees.
• Supplies and materials — office supplies, raw materials, inventory.
• Professional fees — accounting, legal, consulting, and business coaching.
• Business insurance — premiums for general liability, E&O, property, and other business policies.
• Marketing and advertising — website, ads, content creation, business cards.
• Business travel — transportation, lodging, and 50% of meals for qualified business travel (not commuting).
• Interest on business debt — interest paid on a business loan, line of credit, or equipment financing is generally deductible (see IRS Pub 535).
• Home office deduction — if you use part of your home exclusively and regularly for business, a portion of housing costs may be deductible (see IRS Publication 587).
• Retirement plan contributions — contributions to a SEP-IRA, solo 401(k), or SIMPLE IRA for yourself as self-employed.

Capital expenditures — computers, machinery, vehicles used for business — are generally depreciated over time rather than deducted in full the year of purchase. However, IRS Section 179 lets eligible businesses deduct the full purchase price of qualifying equipment in the year placed in service, up to an annual limit (verify the current-year limit at IRS.gov; the 2026 limit is $2,560,000). Bonus depreciation (currently phasing down under the Tax Cuts and Jobs Act) offers an additional first-year deduction percentage. Run both scenarios against your numbers with the Section 179 vs. bonus depreciation calculator before that conversation — a CPA can then help you decide which approach is better for your cash flow and tax situation.

The IRS allows businesses to deduct all "ordinary and necessary" expenses of operating a trade or business under IRC Section 162. An ordinary expense is common in your field; a necessary expense is helpful and appropriate. Maximizing deductions is not aggressive tax strategy — it is claiming what the tax code already permits, with documentation to prove it. This is general education; consult a licensed CPA or enrolled agent for your specific situation.

The single highest-leverage habit: record every business expense when it occurs. Reconstruct records at tax time routinely miss deductible items. Use a dedicated business bank account and credit card so business and personal spending never mix. Every receipt and invoice should be saved — the IRS may audit up to three years back (six if income is substantially understated). See IRS Publication 583 (Starting a Business and Keeping Records) for required record-keeping standards.

Instead of depreciating equipment over several years, Section 179 lets eligible businesses deduct the full purchase price in the year the asset is placed in service, up to the annual limit set by the IRS (see current limit at IRS Publication 946). Qualifying property includes machinery, computers, office furniture, and most business vehicles. Bonus depreciation may allow additional first-year deductions beyond the Section 179 cap — your CPA can calculate the optimal combination.

An S corporation is not a type of entity you form at the state level — it is a federal tax election made with the IRS on Form 2553. A business first forms a C corporation (or an LLC that elects to be treated as a corporation) under state law, then applies for S status with the IRS. The result: the corporation itself pays no federal income tax on most income. Instead, profits and losses flow through to shareholders' individual tax returns, similar to how a partnership or LLC is taxed.

A standard C corporation pays corporate income tax on its profits, and if it distributes dividends to shareholders, those shareholders pay income tax on the dividends again — that is the double taxation S-corp status eliminates. With an S-corp, there is only one level of taxation: at the shareholder level. The IRS S Corporations page outlines the full eligibility rules and election process.

• Must be a domestic corporation (formed in the U.S.).
• No more than 100 shareholders.
• All shareholders must be U.S. citizens or permanent residents — not partnerships, corporations, or most trusts.
• Only one class of stock is permitted (though voting rights can differ).
• Cannot be certain financial institutions, insurance companies, or international sales corporations.

Whether you receive a W-2 or a 1099 depends on how the IRS classifies your working relationship — employee or independent contractor. The classification affects who withholds taxes, what forms you file, and what you owe.

Employers send Form W-2 to workers classified as employees. The employer withholds federal and state income taxes, Social Security, and Medicare from each paycheck and pays the employer's matching share of Social Security and Medicare.

Businesses send Form 1099-NEC to individuals they pay $600 or more as independent contractors. No taxes are withheld. Contractors pay their own income tax and self-employment tax (the employee and employer portions of Social Security and Medicare), typically via quarterly estimated payments.

Payroll is more than writing checks. Each pay period, an employer must calculate gross pay (salary or hours × rate), subtract employee-side withholding (federal and state income tax, Social Security, Medicare), apply any benefit deductions (health insurance, 401(k)), and remit the net amount to the employee. On top of that, the employer owes a matching share of Social Security and Medicare (FICA) taxes and, in most cases, federal and state unemployment tax. Missing a deposit deadline triggers IRS penalties that compound quickly.

• Gross pay — total wages before any deductions (hourly × hours, or full salary for exempt employees).
• Employee withholding — federal/state income tax, plus the employee's 7.65% share of FICA (Social Security 6.2% + Medicare 1.45%).
• Employer taxes — a matching 7.65% FICA share, plus FUTA (federal unemployment tax) and state unemployment tax.
• Benefit deductions — pre-tax (health, FSA, 401(k) contributions) reduce taxable income before withholding is applied.
• Net pay — what actually hits the employee's bank account after all deductions.

The IRS requires employers to deposit withheld taxes on either a monthly or semi-weekly schedule, depending on the size of your payroll. Most new or small businesses start as monthly depositors. Failure-to-deposit penalties escalate the longer the deposit is late, so automating payroll tax deposits is strongly advisable.

The profit and loss statement (P&L) answers: did your business make or lose money over a given time frame? It runs from the top line (total revenue) down through every major cost category to the bottom line (net income or net loss). Lenders, investors, and accountants all rely on it — and it's one of the documents most commonly requested during a small business funding review.

• Revenue (or gross sales) — total income from goods sold or services rendered before any deductions.
• Cost of Goods Sold (COGS) — direct costs tied to producing what you sell (materials, direct labor).
• Gross profit — revenue minus COGS. Shows what's left before overhead.
• Operating expenses — overhead costs like rent, utilities, payroll, marketing, insurance.
• Operating income (EBIT) — gross profit minus operating expenses.
• Net income (or net loss) — what remains after all costs, including interest and taxes.

Lenders typically request 1–2 years of P&Ls (often alongside tax returns) to verify revenue trends and profitability. A P&L showing consistent gross profit margin indicates the business model is sound; one showing shrinking margins or mounting operating losses raises questions about repayment capacity. The SBA's financial management guidance lists the P&L as a core tool for understanding business viability. For the full breakdown of what that margin measures and how to benchmark it, see ClearValue Books' gross margin glossary entry.