Sole proprietors, and single-member LLCs that have not elected corporate tax treatment, report business income and expenses on Schedule C (Form 1040), Profit or Loss From Business. The profit flows to the owner's individual return and, usually, to Schedule SE for self-employment tax. Clean books make Schedule C mostly a mapping exercise.

Part I: income

Part I starts with gross receipts, subtracts returns and allowances, and then cost of goods sold to reach gross profit. Gross receipts should come from your income accounts, not from bank deposits, because deposits include transfers, loans and owner contributions that are not income. If you receive Forms 1099-NEC or 1099-K, their totals should be explainable from your recorded income.

Part II: expenses

Part II lists expense categories such as advertising, car and truck expenses, contract labor, depreciation, insurance, interest, legal and professional services, office expense, rent, repairs, supplies, taxes and licenses, travel, deductible meals, utilities and wages. A chart of accounts that roughly mirrors these lines saves time; see our guide to setting up a chart of accounts.

Some lines need supporting forms or records:

  • Car and truck expenses need mileage records, and Part IV asks about vehicle use
  • Depreciation usually requires Form 4562
  • Business use of home is figured separately; see home office deduction basics

Part III: cost of goods sold

Businesses that sell products report beginning inventory, purchases, labor and materials, and ending inventory. The IRS explains the rules in Publication 334. A year-end inventory count supports the ending figure.

Self-employment tax

Net profit from Schedule C is generally subject to self-employment tax, calculated on Schedule SE. There is no withholding, so most owners make estimated tax payments during the year.

What makes Schedule C hard

Problems almost always come from the books, not the form:

  • Owner draws or personal spending recorded as expenses
  • Loan proceeds recorded as income or loan principal recorded as expense
  • Equipment purchases expensed without a depreciation decision
  • Missing receipts for meals, travel and vehicle costs

Monthly bookkeeping fixes these before they reach the return. Our tax services start from reconciled books for exactly that reason.

Common Schedule C pitfalls

  • Mixing personal and business transactions in one account, which makes expenses hard to support
  • Missing income from payment apps or marketplaces reported on Form 1099-K
  • Deducting personal expenses such as commuting or personal meals
  • Ignoring inventory, by expensing merchandise purchases that are still unsold
  • Skipping estimated tax payments, which can lead to underpayment penalties
  • Forgetting self-employment tax, calculated on Schedule SE

Bookkeeping that maps to Schedule C

Set up your chart of accounts so expense accounts align with Schedule C lines: advertising, car and truck expenses, contract labor, insurance, legal and professional services, office expenses, rent, repairs, supplies, taxes and licenses, travel, meals and utilities. A clean mapping makes the return faster to prepare and easier to review. The IRS's Instructions for Schedule C describe each line.

Key terms

Definitions for terms used in this guide, from our small business glossary:

  • Cost of Goods Sold: Cost of goods sold is the direct cost of the products a business sold during a period.
  • Gross Profit: Gross profit is revenue minus cost of goods sold, before operating expenses.
  • Self-Employment Tax: Self-employment tax is the Social Security and Medicare tax paid by people who work for themselves, calculated on net earnings from self-employment.
  • Chart of Accounts: A chart of accounts is the organized list of every account a business uses to record transactions in its general ledger.
  • Depreciation: Depreciation spreads the cost of a long-lived business asset over the years it is used, rather than deducting it all at once.