When Reselling Counts As Self-Employment
If you buy items to resell, whether it's sneakers, thrifted clothing, retail arbitrage products, or liquidation pallets, and you do it with regularity and intent to profit, the IRS treats you as running a business. That means your income and expenses get reported on Schedule C, and any net profit over $400 is subject to self-employment tax, calculated on Schedule SE.
This is different from casually selling a few personal items you no longer want. Selling your old couch on Facebook Marketplace for less than you paid isn't a business and doesn't create self-employment tax. But if you're sourcing inventory specifically to flip for profit, on eBay, Poshmark, Mercari, Amazon, or elsewhere, that's a business activity in the eyes of the IRS, regardless of whether you have a business license or LLC.
How Self-Employment Tax Actually Works
Self-employment tax is 15.3% of your net profit: 12.4% for Social Security (up to an annual wage base limit that adjusts each year) and 2.9% for Medicare (no cap). This is separate from and in addition to ordinary federal and state income tax. As a W-2 employee, your employer would normally split this cost with you. As a reseller running your own operation, you cover both halves yourself.
The calculation starts with your gross resale revenue, then subtracts your cost of goods sold (what you paid for the inventory), platform fees, shipping supplies, mileage for sourcing trips, and other ordinary business expenses. What's left is your net profit, and that's the number that flows to Schedule SE. You get a small deduction: half of your self-employment tax reduces your taxable income on Form 1040, but it doesn't reduce the self-employment tax itself.
1099-K Forms And What Triggers IRS Attention
Platforms like eBay, Poshmark, and PayPal issue Form 1099-K when your sales exceed the reporting threshold for the year, a number that has been in flux and continues to be adjusted, so check the current-year figure. Getting a 1099-K doesn't automatically mean you owe self-employment tax on the full amount. It reports gross payment volume, not profit. You still subtract your cost of goods and expenses to find your actual taxable profit.
Importantly, not receiving a 1099-K doesn't excuse you from reporting reseller income if you're running it as a business. The IRS expects self-reported income regardless of whether a form was issued.
Paying As You Go Instead Of Getting Surprised
Because no employer withholds tax from resale income, the IRS expects estimated quarterly payments if you'll owe $1,000 or more for the year. These are filed using Form 1040-ES, due in April, June, September, and January. Resellers who skip this and pay everything at once in April often face an unpleasant surprise: a large tax bill plus a penalty for underpayment, even in a profitable year.
The fix isn't complicated, but it does require knowing your numbers throughout the year, not just at tax time. Tracking your cost of goods, fees, and net profit monthly rather than reconstructing it in March gives you an accurate estimate of what you owe and prevents the scramble that comes from discovering a five-figure tax bill after the fact.