Side gig taxes: Schedule C, self-employment tax and quarterly payments

The first year of a side gig usually goes the same way. The money comes in, nobody withholds anything, and in April the bill is bigger than expected. That surprise has a name: self-employment tax. It sits on top of income tax, and it is the part most people miss. This page walks through the three forms that matter, Schedule C, Schedule SE and the quarterly payment voucher, in the order the tax actually happens.

Is it a business? Usually, yes

If you drive, deliver, design, tutor, sell or give advice for pay and you are not anyone's employee for that work, the IRS generally treats you as an independent contractor. That income is taxable whether or not anyone sends you a form. The IRS puts it plainly: "You must report all income on your tax return, even if you don't receive Forms 1099." ¹

Payers may send a Form 1099-NEC, 1099-MISC or 1099-K, usually by the end of January. ¹ For 2026, the general reporting threshold for a payer's information return is $2,000, but that is a rule about when the payer has to send a form, not about whether you owe tax. Your own records are the real source. If the 1099-K is the confusing one, we walk through it in Form 1099-K without double counting.

Step one: Schedule C, the profit

Schedule C is a one-page profit and loss statement. Gross receipts go at the top. Ordinary and necessary business expenses come off: supplies, software, a share of your phone, business miles, fees the platform keeps. What is left is net profit, and net profit is the number everything else is built on. ¹

Two habits make Schedule C easy: a separate account for the gig, and a running list of expenses with receipts. The IRS asks you to keep records of all gig income and expenses through the year, not to rebuild them in April. ¹

Step two: Schedule SE, the tax people forget

When you work for an employer, Social Security and Medicare tax is split. You pay half through withholding and the employer pays the other half. When you work for yourself, you are both sides, and you pay both halves through self-employment tax on Schedule SE. ²

Who owes it. You owe self-employment tax and file Schedule SE if your net earnings from self-employment are $400 or more. ²

How it is figured. The math has three moves:

1. Start with net profit from Schedule C.
2. Multiply by 92.35%. That trims the base the way an employer's share would be excluded from an employee's wages. ⁴
3. Apply the rates: 12.4% for Social Security and 2.9% for Medicare.

The ceiling and the extra. The Social Security part stops once your combined wages and self-employment earnings reach the 2026 wage base of $184,500. Your W-2 wages count first, so a well-paid employee with a small gig may owe only the Medicare part on the gig. The Medicare part has no ceiling, and high earners can also owe the 0.9% Additional Medicare Tax. ²

The half you get back. You deduct one-half of your self-employment tax (not counting the Additional Medicare Tax) in figuring adjusted gross income. ³ It lowers income tax, not the self-employment tax itself. ²

Step three: income tax, and one deduction worth knowing

The same net profit is also ordinary income on your Form 1040, taxed at your regular rates. Many sole proprietors also qualify for the qualified business income deduction, generally up to 20% of qualified business income, subject to limits at higher incomes. That deduction reduces income tax only; it does nothing to self-employment tax. ¹

Step four: paying during the year

The tax system is pay-as-you-go. With no withholding on the gig, the IRS expects estimated payments, due in mid-April, mid-June, mid-September and mid-January. ¹ If you also have a job, there is a simpler route: raise the withholding on your Form W-4 and let your paycheck cover the gig. Withholding counts as paid evenly through the year, which is a quiet advantage. ⁵

We explain the four checkpoints, and the safe-harbor target that keeps the underpayment penalty away, in Estimated taxes in 2026.

What to gather

• Every Form 1099-NEC, 1099-MISC and 1099-K, and your own income records. When a form and your records differ, you report what you actually earned, so keep the records that show it.
• A list of business expenses with receipts, and a mileage log if you drive for the business.
• Your W-2s, since wages count first toward the Social Security wage base.
• Last year's return, for the estimated-tax safe harbor.