Cost Basis and Cost of Goods Sold for Resellers

The single most reassuring fact in reselling taxes is also the one most often missed: you are never taxed on what you sold, only on what you made. The gap between those two numbers is where cost basis and cost of goods sold live. Learn to track them and a $30,000 sales year can turn into a few thousand dollars of taxable profit. Ignore them and you can end up paying tax on money that was never yours to keep. This guide explains both terms in plain language, shows how they flow onto a tax return, and works the math on the kind of items a real reseller actually handles.

Cost basis: what a single item cost you

Cost basis is what you paid to acquire one specific item, plus the costs of getting it ready to sell. If you buy a jacket at a thrift store for $8, your basis in that jacket is $8. If you also paid $2 to dry-clean it before listing, many resellers fold that into the item's cost as well. When the jacket sells, your basis is the number you subtract from the sale to find the profit. The concept matters because profit, not the sale price, is what the tax system cares about. The IRS explains basis as generally the cost of property in its guidance for small businesses at IRS.gov.

The practical challenge is that resellers buy in bulk, at yard sales, estate sales, and clearance racks, often without a tidy receipt per item. That is fine, but it puts the burden on you to record a reasonable basis at the moment you source, because reconstructing it a year later from memory is how deductions get lost. A sourcing log that captures date, item, and what you paid is the raw material for every profit calculation you will make. Our guide to sourcing inventory and tracking basis covers how to keep that record without slowing down a buy.

Cost of goods sold: basis, totaled up for the year

Cost of goods sold, usually shortened to COGS, is the same idea rolled up across everything you sold in a year. It is the total cost basis of the items that actually left your hands and generated revenue. Crucially, it is the cost of items sold, not the cost of everything you bought. Inventory you purchased but have not sold yet is not part of this year's COGS; its cost waits on the shelf, figuratively, until the year it sells. On a Schedule C (Form 1040), which is where most sole-proprietor resellers report, COGS gets its own section and reduces your gross receipts before you even reach your other expenses. See the IRS Schedule C page for the form itself.

A worked example: one item

Say you buy a pair of used designer sneakers for $40, spend $3 on cleaning supplies attributable to them, and list them on eBay. They sell for $120. The buyer also pays $12 shipping, which passes through to the carrier. Start with the $120 item price. Subtract your cost basis of $43. Subtract the platform fees, which on eBay run roughly 13.6 percent of the buyer-paid total plus a fixed per-order fee, so call it about $18 here. Subtract the actual shipping cost you paid, say $11 against the $12 collected. What is left, roughly $48, is your profit on that sale. You were paid $132 in gross, but you made about $48. That $48 is the figure that flows toward taxable income, not the $132.

A worked example: a full year

Now scale it. Over a year you sell 300 items for $28,000 in total item revenue. Your records show the items you sold cost you $9,000 to acquire, which is your COGS. Platform fees came to $4,000, shipping you paid was $2,500, and supplies and mileage added another $1,500 in deductible expenses. Start at $28,000, subtract $9,000 COGS to get $19,000 gross profit, then subtract $8,000 in operating expenses. Your net profit is about $11,000. That is the number self-employment and income tax are figured on, and it is a long way from the $28,000 that might have looked alarming on a year-end statement. To see how that net profit drives a self-employment tax estimate, and whether your activity reads as a business at all, run your figures through the 1099-K Checker.

Why this protects you at tax time

A Form 1099-K, when you receive one, reports gross payments, not profit. Without basis and COGS records, you have no clean way to show the IRS that the gross figure overstates what you actually earned, and you risk being taxed as if your costs were zero. With those records, the return tells the true story: revenue in, cost of the goods out, expenses out, profit taxed. This is also why casual sellers clearing out a closet at a loss usually owe nothing, because their items sold for less than they originally paid, though personal-item losses are generally not deductible either. The deductible expenses guide picks up where COGS leaves off.

This article is general information, not tax advice. Tax rules and the treatment of basis, inventory, and cost of goods sold depend on your situation; confirm the current rules with the IRS at IRS.gov and with a qualified tax professional before you file. Start at the Reseller Math hub for the tools referenced above.