Sole proprietorship accounting is built around one fact: the IRS treats the business as a “disregarded entity,” so the business itself files no return. Every dollar of profit and every deductible expense flows onto your personal Form 1040 through Schedule C. You keep one set of books, you’re the only taxpayer, and your “paycheck” is simply the profit, taxed whether you withdraw it or leave it sitting in the business account. That single idea shapes the bookkeeping, the tax return, and the payment schedule.
A corporation, by contrast, keeps its own books, files its own return on Form 1120, and treats owner compensation as salary or dividends.1Internal Revenue Service. About Form 1120, U.S. Corporation Income Tax Return None of that applies to you. Your financial statements are internal tools for calculating net profit; they don’t get filed anywhere.
Separate the Money Even Though the Law Doesn’t
The law sees no boundary between you and your business, but your bookkeeping should. Mixing personal and business transactions in one account creates a mess at tax time, weakens your position in an audit, and buries deductions you’re entitled to claim.
The IRS requires records that clearly show income and expenses.2Internal Revenue Service. What Kind of Records Should I Keep Open a dedicated business checking account. Run all business income and expenses through it. Keep personal spending out of it. That one habit makes every other part of proprietorship accounting dramatically easier.
Save receipts for every business expenditure, keep copies of invoices you send, and hang onto bank and credit card statements. Expensive software isn’t required to start. A simple spreadsheet tracking income and expenses by category works fine for many sole proprietors, and accounting software becomes useful mostly when transaction volume grows.
Cash or Accrual: Choose Your Accounting Method
Your accounting method determines when you recognize income and expenses. You lock in your choice when you file your first Schedule C, and switching later requires IRS approval.3Internal Revenue Service. Publication 334 – Tax Guide for Small Business
Most sole proprietors use the cash method because it mirrors what the bank account shows. Income counts when the money hits your account; expenses count when you actually pay them. An invoice you send in December but the client pays in January belongs to next year’s income. The cash method also lets you time certain deductions by choosing when to pay a bill, giving you some control over taxable income across years.
The accrual method counts income when you earn it and expenses when you incur them, regardless of when cash changes hands. It gives a more accurate snapshot of profitability at any moment, but it’s more complex and can leave you paying tax on income you haven’t yet collected.
Businesses that carry inventory generally have to use accrual for sales and purchases, unless they qualify as a small business taxpayer. That threshold is an inflation-adjusted figure in the range of $30 to $31 million of average annual gross receipts.4Office of the Law Revision Counsel. 26 U.S. Code 448 – Limitation on Use of Cash Method of Accounting The vast majority of sole proprietors sit well below it and can use cash regardless.
Owner’s Capital and Owner’s Draws
Sole proprietors don’t receive a salary or dividends. Two equity accounts track the owner’s financial relationship with the business.
Owner’s Capital represents your total investment. It rises when you contribute personal money or assets, and it rises by the amount of net income earned each period. A net loss reduces it. Think of the balance as a running score of how much value you have tied up in the business.
Owner’s Draws track money you take out for personal use. Draws are not business expenses and do not reduce your taxable income. They reduce your equity. Whether you withdraw $5,000 or leave every penny in the business account, the full net profit is taxed the same way. The draw account exists for bookkeeping clarity so you can see how much you’ve pulled out over the year.
Deductions That Lower Your Taxable Profit
A deductible expense has to be both ordinary (common in your industry) and necessary (helpful and appropriate). Necessary doesn’t mean indispensable.5Internal Revenue Service. Ordinary and Necessary Beyond obvious costs like supplies, advertising, and professional services, a handful of deductions carry real weight for sole proprietors.
Home Office
If you use part of your home regularly and exclusively for business, you can deduct a portion of your housing costs. The simplified method allows $5 per square foot of dedicated workspace, up to 300 square feet, capped at $1,500.6Internal Revenue Service. Simplified Option for Home Office Deduction The regular method applies your business-use percentage to actual expenses like rent, utilities, and insurance. It takes more recordkeeping but often produces a larger deduction.
Business Mileage
When you use a personal vehicle for business, you can deduct either actual vehicle expenses or the standard mileage rate. The 2026 IRS standard mileage rate is 72.5 cents per mile.7Internal Revenue Service. IRS Sets 2026 Business Standard Mileage Rate at 72.5 Cents Per Mile, Up 2.5 Cents Keep a log noting date, destination, business purpose, and miles. Without a log, the deduction is nearly impossible to defend in an audit.
Self-Employed Health Insurance
Sole proprietors who buy their own health insurance can deduct 100% of premiums paid for themselves, a spouse, and dependents. It’s claimed as an adjustment to gross income on Schedule 1, not on Schedule C, so you get it whether you itemize or take the standard deduction.8Internal Revenue Service. Instructions for Form 7206 You must have a net profit on Schedule C to qualify, and the deduction is not available for any month you were eligible to participate in an employer-sponsored plan through your own job or your spouse’s.
Retirement Contributions
A SEP IRA lets you contribute up to 25% of net self-employment earnings, with a $72,000 maximum for 2026.9Internal Revenue Service. SEP Contribution Limits (Including Grandfathered SARSEPs) Contributions are deductible and reduce adjusted gross income. A Solo 401(k) can allow higher contributions at lower income levels because it has both an employee and employer component.
Qualified Business Income
Under Section 199A, sole proprietors may deduct up to 20% of qualified business income. If taxable income is below roughly $201,750 (about $403,500 for married couples filing jointly), the full 20% generally applies with no additional restrictions. Above those thresholds the deduction phases out, and certain service businesses such as consulting, law, and accounting face stricter limits. The QBI deduction is claimed on your personal return and does not appear on Schedule C.
Schedule C: Where the Books Meet the Return
Schedule C is where a year of bookkeeping becomes a tax document. It starts with gross receipts, subtracts cost of goods sold if applicable, and lists deductible expenses by category to reach net profit or loss. That figure flows to your Form 1040.10Internal Revenue Service. About Schedule C (Form 1040) – Profit or Loss From Business
Report business income and expenses on Schedule C regardless of how much or how little you earned. The commonly cited $400 threshold applies to self-employment tax, not to Schedule C. If net self-employment earnings reach $400 or more, you also file Schedule SE.11Internal Revenue Service. Schedule C and Schedule SE Under $400 in net earnings, you still report the income on Schedule C and Form 1040.
Self-Employment Tax
You pay both the employer and employee halves of Social Security and Medicare. The combined self-employment tax rate is 15.3%: 12.4% Social Security and 2.9% Medicare.12Internal Revenue Service. Self-Employment Tax – Social Security and Medicare Taxes Before applying that rate you multiply net earnings by 92.35% to get the taxable base, which mirrors the employer-side treatment for traditional employees.
The 12.4% Social Security portion applies only to net earnings up to $184,500 in 2026.13Social Security Administration. Contribution and Benefit Base Earnings above the cap escape that portion. The 2.9% Medicare portion has no cap. If combined wages and self-employment income exceed $200,000 ($250,000 for married filing jointly), an additional 0.9% Medicare tax applies to the amount above the threshold.14Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
The calculation runs on Schedule SE. One offset: you can deduct half of your self-employment tax on Schedule 1 when calculating adjusted gross income. That reduces your income tax but not the self-employment tax itself.
Quarterly Estimated Payments
Employees have taxes withheld from every paycheck. Sole proprietors don’t. You pay as you go through quarterly estimated payments. For 2026 the due dates are April 15, June 15, September 15, and January 15, 2027.15Internal Revenue Service. 2026 Form 1040-ES If you file your 2026 return and pay the full balance by February 1, 2027, you can skip the January payment.
Underpayment triggers a penalty calculated on each shortfall for the number of days it remains unpaid. You avoid the penalty by meeting any one of these safe harbors:
- Your total tax due after withholding and refundable credits is under $1,000 when you file.
- You paid at least 90% of the tax shown on your 2026 return through estimated payments and withholding.
- You paid at least 100% of the tax shown on your 2025 return. If your 2025 adjusted gross income exceeded $150,000 ($75,000 if married filing separately), the threshold is 110%.
The prior-year safe harbor is the easiest because you know the number in advance. Many sole proprietors divide last year’s total tax by four and pay that amount each quarter, adjusting only if income changes dramatically.16Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
When You Need an EIN and When You Need a DBA
Many sole proprietors can use a Social Security Number for tax filing. Certain situations require a separate Employer Identification Number instead: hiring employees, filing excise tax returns, or contributing to a Keogh retirement plan. An EIN is free from the IRS, and a sole proprietor generally needs only one regardless of how many trade names they operate.17Internal Revenue Service. Instructions for Form SS-4 Later incorporation or forming a partnership requires a new EIN.
Separately, if you operate under any name other than your own legal name, most states require you to register a fictitious business name, sometimes called a DBA. Requirements and fees vary by state and county. Failing to register when required can result in fines and may prevent you from enforcing contracts made under the unregistered name.