Self-employed accounting: what a sole proprietor actually has to keep, and when

What self-employed accounting has to produce

Corporate accounting exists to inform investors and lenders. Sole-proprietor accounting exists to answer four questions, and everything you keep should serve one of them:

1. How much did the business earn this year? Gross receipts, on a cash basis, per business.
2. What did it cost to earn it? Expenses by Schedule C category, each with evidence.
3. How much tax do I owe, and when? Income tax plus self-employment tax, paid quarterly.
4. Who owes me money right now? Unpaid invoices, so cash keeps arriving.

Notice what is missing: a balance sheet, accrual adjustments, a general ledger with debits and credits. A sole proprietor with no inventory and no employees does not need them, and software built for companies that do will make you maintain them anyway.

The structure: three records and a boundary

The boundary first. Open a separate bank account and card for the business and run everything through them. It is the single change that makes the rest of this page easy. Without it, every statement has to be picked through to separate the business from the groceries, and every personal line that slips through is a deduction you were not entitled to.

Inside that boundary there are three records:

The income record: invoices

Every job gets an invoice, even when the customer pays on the spot. The invoice is what says who paid, for what, when, and whether sales tax was part of it. Paid invoices, totalled, are your gross receipts. Unpaid ones are your receivables.

The expense record: receipts with categories

Every purchase gets a Schedule C category and, wherever possible, a photo of the receipt attached, on the day. Card statements are imported to catch what was never photographed.

The mileage log

Date, miles, purpose, recorded as you drive. For a contractor who visits customers it is often the second-largest deduction after materials.

If you run more than one activity, say a trade and a rental property, each needs its own set of these three records, because they file on different forms with different tax treatment.

The monthly routine

The books stay small if they are touched monthly. An hour at the start of each month, with the previous month's statements, covers it:

1. Import the bank and card statements. Mark each line: income, taxable expense, or non-taxable (transfers between your own accounts, loan principal, personal). Give expenses a category.
2. Reconcile income. Every deposit should match a paid invoice or be explained. A deposit with no invoice is either a job you forgot to bill properly or money that is not income; find out which.
3. Resolve duplicates. Receipts photographed during the month will match card lines you just imported. Keep the receipt, drop the duplicate.
4. Chase what is owed. Look at overdue invoices and send reminders. Cash flow is an accounting problem before it is a sales problem.
5. Read the profit figure. Income minus expenses, year to date. That number, times roughly a quarter to a third depending on your bracket, is what you should have set aside for tax.

Self-employment tax, estimates and the deductions specific to you

An employee's Social Security and Medicare are split with the employer. A sole proprietor pays both halves as self-employment tax: 15.3% of 92.35% of net profit, made up of 12.4% Social Security up to the annual wage base and 2.9% Medicare with no cap. It is calculated on Schedule SE and added to your income tax, and half of it is deductible on Schedule 1.

Because nothing is withheld, the IRS expects four estimated payments a year, due April 15, June 15, September 15 and January 15, using Form 1040-ES. Pay at least last year's total tax (110% of it if your AGI was over $150,000), or 90% of this year's, and there is no penalty.

Three deductions belong to the self-employed specifically, and none of them appears on Schedule C:

• Half of self-employment tax, on Schedule 1.
• Health insurance premiums for you and your family, if you are not eligible for an employer plan, also on Schedule 1.
• Retirement contributions to a SEP-IRA or solo 401(k), which can be large: up to 25% of net self-employment earnings for a SEP.

And most sole proprietors qualify for the 20% qualified business income deduction, which the 2025 tax law made permanent. All four depend on one number: net profit from the books.

Year end: what to hand over

Whether you file yourself or use a preparer, year end is a handover of the same package: gross receipts per business, expenses by Schedule C line with the entries behind them, the mileage total and log, the 1099-NEC and 1099-K forms clients and platforms sent you, the 1098 from any lender, the estimated payments you made and when, and last year's return. For a rental, the same per property on Schedule E lines.

A preparer will accept a folder of statements and charge you for the hours it takes to turn them into that package. Software that has been categorising all year produces it as a report. That is the whole economic case for keeping the books as you go: the work is the same either way, but doing it on the day is a few seconds per entry and doing it in April is a project.

Sole proprietor, LLC or S corporation?

A single-member LLC changes your legal liability but not your accounting: it is still taxed as a sole proprietorship on Schedule C, and everything above applies unchanged. An S-corporation election changes the accounting substantially, because you become an employee of your own company: payroll, a reasonable salary, a corporate return, and books that a preparer will insist on. It can save self-employment tax once profit is comfortably above what a reasonable salary would be, but it costs real money and time to run. Decide with a professional, on a year of clean Schedule C numbers, rather than on a guess.