DIY Small Business Taxes: A Guide for Self-Funded Entrepreneurs

You don't need a CPA to file clean, compliant small business taxes. What you need is a system: know what you owe, track your deductions, pay quarterly estimates on time, and file the right forms. This guide walks you through each step so you can handle your taxes with confidence.

Self-employed business owners owe 2 types of federal tax: self-employment tax and income tax. The self-employment tax rate is 15.3% on net earnings — 12.4% for Social Security and 2.9% for Medicare. That applies to net earnings of $400 or more. On top of that, you owe federal income tax at your ordinary bracket rate, plus any applicable state income tax.

Most employees never see the full 15.3% because their employer covers half. When you're self-employed, you cover all of it. The IRS does let you deduct half of the self-employment tax when calculating your adjusted gross income, which reduces your income tax bill — but the self-employment tax itself still applies in full.

A working bookkeeping system doesn't have to be complicated — it has to be consistent. Open a dedicated business bank account and run all business income and expenses through it. That single step eliminates most of the confusion at tax time and makes it much harder for a court to question whether your business is a real separate entity.

From there, the system is straightforward. Reconcile your transactions weekly — not monthly, not at year-end. Store digital copies of receipts as you go. The IRS requires you to keep records that support the income and deductions you claim, and hunting for a receipt 11 months after the fact is a problem you don't want.

Most bookkeeping software connects directly to your bank account and categorizes transactions automatically. That's not a luxury — it's the difference between a tax filing that takes a few hours and one that takes a few weeks.

Your business structure determines which forms you file and how your income gets taxed. This is one of the decisions that catches people off guard — the structure you choose at formation has real tax consequences every year after.

Sole proprietor or single-member LLC

Your business income flows directly onto your personal return. You report profit and loss on Schedule C (Form 1040) and pay self-employment tax on net earnings of $400 or more via Schedule SE.

Multi-member LLC or partnership

The business files Form 1065 and issues each member a Schedule K-1 showing their share of income, deductions, and credits. Each member then reports that on their personal return.

S Corporation election

If your LLC elected S Corp status, you must pay yourself a reasonable salary as a W-2 employee. The business files Form 1120-S. This structure can reduce self-employment tax on distributions above your salary, but it adds payroll complexity — worth talking through with a tax professional before electing.

The IRS allows deductions for business expenses that are ordinary and necessary — meaning common in your industry and directly related to running your business. Deductions reduce your net profit, which reduces both your income tax and your self-employment tax. That makes them worth tracking carefully.

Common deductible expenses include home office costs, business mileage, equipment, software, professional services, and health insurance premiums for self-employed individuals. For the home office deduction, the IRS requires the space be used exclusively and regularly for business — a corner of your living room where you also watch TV doesn't qualify. You can use either the simplified method ($5 per square foot, up to 300 square feet) or the actual expense method.

The line to watch: a deduction has to be genuinely business-related. A luxury watch, a personal vacation with one business meeting attached, or a meal with a friend who happens to be a client — these are the kinds of claims that draw scrutiny. Take the deductions you're entitled to. Don't stretch them.

If you expect to owe at least $1,000 in federal taxes for the year, the IRS requires you to pay estimated taxes quarterly using Form 1040-ES. Missing these payments doesn't just mean a bigger bill in April — you can also owe an underpayment penalty on top of what you owe.

The 4 payment deadlines generally fall in April, June, September, and January of the following year. You can pay online through the IRS Direct Pay portal at irs.gov/payments — no account required, no fee. To estimate what you owe each quarter, use your prior year's tax liability as a baseline or estimate based on your current year income.

A simple approach: set aside 25–30% of every payment you receive into a separate savings account. When a quarterly deadline arrives, you'll have the money ready. Most business owners who get into trouble with estimated taxes aren't underpaying on purpose — they just didn't build the habit early.

The forms you file depend on your business structure, but most self-employed entrepreneurs filing for the first time will work with a core set. Knowing which forms apply to you before tax season starts saves real time.

• Schedule C (Form 1040) — reports your business profit or loss if you're a sole proprietor or single-member LLC
• Schedule SE (Form 1040) — calculates the self-employment tax you owe on net earnings of $400 or more
• Form 1040-ES — used to calculate and pay quarterly estimated taxes
• Form 1065 — the annual return for multi-member LLCs and partnerships, accompanied by Schedule K-1 for each member
• Form 1099-NEC — issued to contractors you paid $600 or more during the year; due to recipients by January 31
• Form 1120-S — the annual return for LLCs that elected S Corporation status

You can file federal taxes electronically through IRS Free File if your adjusted gross income is $79,000 or less, or use IRS Direct File if you're in a participating state. Commercial tax software certified by the IRS also supports e-filing for self-employed filers.

Handling your own taxes is realistic for most self-employed entrepreneurs with straightforward income and expenses. There are situations, though, where the cost of a professional is worth it — and recognizing them early is cheaper than fixing a mistake later.

Consider bringing in a tax professional if you're electing S Corporation status for the first time, you have employees and need to run payroll, you received a notice from the IRS, your income changed significantly from the prior year, or you're unsure whether a major expense qualifies as a deduction. You don't need a CPA specifically — an Enrolled Agent (EA) is a federally authorized tax practitioner with unlimited rights to represent you before the IRS, and EAs often charge less than CPAs for tax work.

If you're preparing your own return, you don't need any special credentials from the IRS. A Preparer Tax Identification Number (PTIN) is only required for paid preparers — people who prepare returns for others for compensation. Filing your own business taxes doesn't require one.