Schedule C (Form 1040): Income, Deductions, and Filing

Schedule C on Form 1040 is the attachment sole proprietors use to report business income and expenses, producing a single net profit or loss that carries over to the individual tax return. You file one if you run a business or practice a profession on a regular, ongoing basis with the aim of making a profit. The number the form produces drives more than just your income tax: it also determines your self-employment tax, feeds the qualified business income deduction, and affects your eligibility for self-employed retirement contributions.¹

Who Has to File Schedule C

If you run an unincorporated business by yourself, you’re a sole proprietor, and Schedule C is your form. Single-member LLCs use it too, because the IRS treats them as disregarded entities unless the owner elects corporate treatment by filing Form 8832.²

Married couples who jointly own an unincorporated business can elect qualified joint venture status. Each spouse then files a separate Schedule C for their share of income and expenses, so both build their own Social Security and Medicare earnings records.³

A smaller group of workers called statutory employees also uses Schedule C. The law treats them as employees for Social Security and Medicare withholding but as independent contractors for expense purposes. The category covers certain delivery drivers, full-time life insurance agents, home workers who process materials the payer supplies, and full-time traveling salespeople. If you’re one, the “Statutory employee” box on your W-2 will be checked, and you deduct your work-related expenses directly on Schedule C.⁴

One boundary matters up front: Schedule C is only for activities pursued with a real profit motive. If your side project consistently loses money and looks like a hobby, the IRS can reclassify it. You’d still owe tax on any revenue, but you couldn’t deduct expenses against other income. A common reference point is the three-of-five-year test: showing a net profit in at least three of the past five consecutive years, the IRS generally presumes a business.⁵ Falling short doesn’t automatically make you a hobbyist. The agency also weighs whether you keep accurate books, how much time and effort you invest, whether you depend on the income, and whether you’ve changed methods to improve profitability.⁶

What to Have Ready Before You Start

Pull a few basics together first. You’ll need the legal name of your business, its address, and a six-digit Principal Business or Professional Activity Code identifying your industry. The full list of codes appears at the end of the Schedule C instructions. The right one matters more than it looks: the IRS uses it to compare your income and expense ratios against similar businesses during automated screening.⁷

You also need to know your accounting method. Most sole proprietors use cash: income counts when you receive it, expenses when you pay them. Accrual, which recognizes transactions when they happen regardless of cash flow, is more common in larger operations or businesses that carry inventory. Changing methods after your first year requires filing Form 3115 to request IRS approval.⁸

Reporting Income and Cost of Goods Sold

Part I captures gross receipts or sales: every dollar the business brought in before subtracting anything. That includes amounts reported to you on 1099-NEC forms, cash sales, credit card receipts, and other business revenue. Smaller items like interest on a business bank account go here too.

If you sell physical products, Part III walks you through cost of goods sold. You’ll enter inventory at the start of the year, add purchases and labor costs tied to production, and subtract inventory remaining at year-end. The difference is the direct cost of goods you actually sold, and it gets subtracted from gross receipts to give you gross profit.⁹ Service businesses with no inventory skip Part III.

Deducting Business Expenses

Part II is where most of the tax savings show up. It lists standard categories including advertising, insurance premiums, legal and professional fees, office supplies, and utilities. Premiums for business liability or malpractice coverage go here. Owner health insurance is handled separately, on Form 7206.

Small equipment purchases have a useful shortcut. The de minimis safe harbor election lets you deduct items costing $2,500 or less per invoice without depreciating them over multiple years. Software subscriptions, a printer, or a desk all qualify as long as you make the election on your return.¹⁰

Business meals are 50% deductible when you or an employee are present and the meal isn’t lavish. The temporary 100% deduction for restaurant meals expired after 2022, so the 50% limit applies for 2026. Entertainment expenses like concert tickets or sporting events are no longer deductible.¹¹

Part V catches expenses that don’t fit the preprinted categories: professional association dues, bank service charges, continuing education, and similar costs. Every deduction should be backed by a receipt, invoice, or bank statement. The IRS doesn’t ask for documentation when you file, but you’ll need it if the return gets examined.

Home Office Deduction

If part of your home is used exclusively and regularly as your principal place of business, you can deduct a portion of your housing costs. Exclusively is the key word: the space can’t double as a guest room or playroom, and incidental or occasional use doesn’t count.¹²

There are two calculation options. The simplified method gives you $5 per square foot of dedicated business space, up to 300 square feet, capping the deduction at $1,500. No depreciation calculation, no allocation of utility bills.¹³

The regular method uses Form 8829 and lets you deduct a proportional share of actual expenses such as mortgage interest, property taxes, utilities, insurance, and repairs, based on the percentage of your home devoted to business use. This method also allows depreciation on the business portion of your home, which the simplified method does not. A large home office or high housing costs usually make the regular method worth the extra work.¹³

Vehicle Expenses

Part IV asks for details on business use of your vehicle: total miles driven, business miles, and commuting or personal miles. Commuting miles are never deductible.

You pick between two methods. The standard mileage rate for 2026 is 72.5 cents per mile; multiply it by your business miles.¹⁴ The actual expense method requires tracking every cost tied to the vehicle: gas, oil changes, tires, insurance, registration fees, and depreciation. You then deduct the business-use percentage. Actual expenses can produce a larger deduction when vehicle costs are high relative to miles driven, but the recordkeeping is heavier. Whichever method you choose, keep a contemporaneous mileage log. It is the single most common audit weak spot for sole proprietors.

Depreciation and Section 179

Larger equipment that lasts more than a year, such as computers, furniture, or specialized tools, is normally depreciated over its useful life rather than deducted all at once. Two provisions let many sole proprietors write off the full cost in the year of purchase.

Section 179 allows immediate expensing of qualifying business assets up to $2,560,000 for 2026. The deduction phases out dollar-for-dollar once total equipment purchases exceed roughly $4,090,000, targeting it at small and mid-sized businesses. The Section 179 deduction can’t create or increase a net loss, so it’s limited to your taxable business income for the year.

Bonus depreciation, which had been phasing down, was restored to 100% by the One Big Beautiful Bill Act for qualified property acquired after January 19, 2025. Unlike Section 179, bonus depreciation can generate a loss. For a $30,000 vehicle or $15,000 piece of equipment, these provisions often let you deduct the entire cost in year one rather than spreading it over five or seven years. Depreciation details are reported on Form 4562, which gets attached to Schedule C.

How the Bottom Line Flows Into Your 1040

The net profit from Schedule C line 31 flows to Schedule 1 of your Form 1040 and becomes part of adjusted gross income. That single number then drives several downstream calculations that catch new sole proprietors off guard.

Self-Employment Tax

If your net self-employment earnings are $400 or more, you owe self-employment tax, calculated on Schedule SE. The rate is 15.3%: 12.4% for Social Security and 2.9% for Medicare.¹⁵ The Social Security portion applies only up to the wage base, which is $184,500 for 2026.¹⁶ Medicare has no cap. If your self-employment income exceeds $200,000 (single) or $250,000 (married filing jointly), an additional 0.9% Medicare tax applies to the excess.¹⁷

You do get one offset: half of your self-employment tax comes off adjusted gross income on Schedule 1. That reduces your income tax, but not the SE tax itself.

Qualified Business Income Deduction

Section 199A lets eligible sole proprietors deduct up to 20% of qualified business income, which can substantially reduce the income tax owed on Schedule C profits. For 2026, the deduction is generally available without limitation if taxable income falls below roughly $203,000 (single) or $406,000 (married filing jointly). Above those thresholds, the deduction phases down based on wages paid and property held by the business, and can be restricted or eliminated for specified service businesses like law, accounting, and consulting. The deduction is claimed on Form 1040, not on Schedule C.

Self-Employed Health Insurance

Health insurance premiums you pay for yourself, your spouse, and your dependents are deductible, but not on Schedule C. You calculate the deduction on Form 7206 and report it on Schedule 1. The plan must be established under the business, and you can’t claim the deduction for any month you were eligible for an employer-sponsored plan through a spouse or other source.¹⁸ This is an above-the-line deduction, reducing AGI whether or not you itemize. Premiums you can’t deduct on Form 7206 may still count as medical expenses on Schedule A if you itemize and exceed the 7.5% of AGI floor.

Estimated Taxes Through the Year

Sole proprietors have no employer withholding taxes from a paycheck, so the IRS expects you to pay as you go through quarterly estimated tax payments. You’re generally required to pay estimates if you expect to owe $1,000 or more for the year after subtracting withholding and refundable credits.¹⁹

The 2026 payment deadlines:

First quarter: April 15, 2026
Second quarter: June 15, 2026
Third quarter: September 15, 2026
Fourth quarter: January 15, 2027

You can skip the January payment if you file your 2026 return and pay the full balance by February 1, 2027.¹⁹

Missing a deadline triggers an underpayment penalty based on the shortfall and how long it went unpaid. Two safe harbors protect you: paying at least 90% of your current-year tax, or paying 100% of last year’s tax. If your prior-year AGI exceeded $150,000 ($75,000 if married filing separately), the prior-year safe harbor rises to 110%.²⁰

When You Report a Loss

If expenses exceed income, the net loss flows to Schedule 1 and reduces other taxable income, such as wages from a day job or a spouse’s earnings on a joint return. This is one of the real advantages of business status over hobby classification.

Two limits sit in front of a large loss. The at-risk rules generally prevent you from deducting more than the amount you have financially at stake in the business. The excess business loss limitation then caps how much business loss can offset non-business income in a single year: for 2026, roughly $256,000 for single filers and $512,000 for joint filers. Any disallowed loss converts into a net operating loss carryforward for use in future years.²¹

Records to Keep, and for How Long

Every number on Schedule C should trace back to a source document: bank statements, receipts, invoices, 1099 forms, mileage logs, contracts. The IRS doesn’t mandate any particular system, but whatever you use has to clearly capture income and expenses and let you rebuild the return if questioned.

Retention periods vary:

Three years from filing for most supporting documents.
Six years if you underreported gross income by more than 25%.
Seven years if you claimed a loss from worthless securities or bad debt.
Indefinitely if you didn’t file a return for a given year.

Records tied to business property (purchase price, improvements, depreciation schedules) should be kept until at least three years after you sell or dispose of the asset, because those records determine the gain or loss you report at that point.²²

Filing, Fixing Mistakes, and Penalties

Schedule C attaches to your Form 1040 or 1040-SR and is filed by the standard April deadline, or October if you extend. E-filing is faster and gives immediate confirmation. Paper returns go to the IRS processing center assigned to your region.⁹

Found an error after filing? File Form 1040-X, the amended individual return. Attach a corrected Schedule C, explain the change in Part II of the amendment, and sign it. Most tax software supports e-filing amendments. Processing typically takes 8 to 12 weeks and can stretch to 16.²³

Underreporting income or failing to pay carries a failure-to-pay penalty of 0.5% of the unpaid tax per month or partial month the balance remains outstanding, capped at 25%.²⁴ Refunds on e-filed returns generally arrive within three weeks; paper returns take six weeks or more.²⁵

1
Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship)
2
Internal Revenue Service. Single Member Limited Liability Companies
3
Internal Revenue Service. Election for Married Couples Unincorporated Businesses
4
Internal Revenue Service. Statutory Employees
5
Legal Information Institute. Three-of-Five Test
6
Internal Revenue Service. Heres How to Tell the Difference Between a Hobby and a Business for Tax Purposes
7
Internal Revenue Service. Instructions for Schedule C (Form 1040) – Line B
8
Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method
9
Internal Revenue Service. Instructions for Schedule C (Form 1040)
10
Internal Revenue Service. Tangible Property Final Regulations – A De Minimis Safe Harbor Election
11
Internal Revenue Service. Tax Cuts and Jobs Act – Businesses
12
Internal Revenue Service. Publication 587, Business Use of Your Home
13
Internal Revenue Service. Simplified Option for Home Office Deduction
14
Internal Revenue Service. IRS Sets 2026 Business Standard Mileage Rate at 72.5 Cents Per Mile
15
Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
16
Social Security Administration. Contribution and Benefit Base
17
Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
18
Internal Revenue Service. Instructions for Form 7206 (Self-Employed Health Insurance Deduction)
19
Internal Revenue Service. 2026 Form 1040-ES Estimated Tax for Individuals
20
Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
21
Internal Revenue Service. Instructions for Schedule C (Form 1040) – Excess Business Loss Limitation
22
Internal Revenue Service. How Long Should I Keep Records
23
Internal Revenue Service. Instructions for Form 1040-X (Rev. December 2025)
24
Internal Revenue Service. Failure to Pay Penalty
25
Internal Revenue Service. Refunds – When to Expect Your Refund