Which records should a reseller keep for every item so cost of goods and real profit stay accurate?

The short list of fields that actually earns its keep

A useful item record is smaller than most people expect. You need the SKU, the date and place you bought it, what you paid, any prep cost you want to count such as dry cleaning or a replacement part, the date you first listed it, the channel it eventually sold on, the gross sale price, the fees deducted, the shipping you paid, and the payout that landed. Ten fields, filled once at intake and once at sale. Everything else, including brand, size, and condition notes, belongs in your listing details rather than your money record, because those fields are for selling, not for accounting.

Attach that record to the SKU, not to a marketplace. This is the same discipline that keeps cross-listing sane, and it pays off twice here. An item that was listed on three channels, delisted, relisted, and finally sold on the fourth has one cost and one profit, and it should live in one row. If your only record of an item is the order detail on the platform that happened to sell it, you have no way to see the months it sat elsewhere, and no way to compare channels honestly when you decide where to focus next season. Related: What is the best way to name SKUs when the same item is listed on several marketplaces?

Keep reading: The Oversell Problem for Resellers, Selling on Multiple Platforms, Keeping Prices in Sync. See how RelistSync helps you multi-platform price and inventory sync for resellers.

Splitting a lot purchase without guessing later

Most sourcing does not arrive one item at a time. You buy a box, a rack, an estate lot, or a bag priced by weight, and later you are trying to work out what a single sweater from it cost you. Pick one allocation method and use it every time. Even split across sellable pieces is the simplest and is defensible when the items are broadly similar. Allocation by expected resale value is more accurate for mixed lots where one piece carries most of the value. Splitting by weight works for bulk clothing buys. What matters is choosing one, writing it down, and not switching per lot because a different method would flatter a particular sale.

Give each purchase a lot identifier and put it on every item record that came out of it. That single field answers questions you will actually ask: whether a source is worth going back to, how much of a lot is still unsold six months on, and what the discards cost you. Count the unsellable pieces in the allocation too. If a third of a bag was stained or broken, the pieces you can sell carry the cost of the ones you cannot, and pretending otherwise makes every item in that lot look more profitable than it was. Related: Inventory as a Single Source of Truth

Record what the marketplace actually kept, not the headline rate

The number a platform advertises as its selling fee is rarely the whole deduction. Depending on the channel there can be a payment processing charge, a per order fixed amount, an optional promoted listing rate you agreed to, a shipping label cost, and sometimes a currency or regulatory line. Typical total take across the major consumer marketplaces tends to land in a range wide enough that you cannot substitute one channel's assumption for another. Rather than model it, read the actual payout on the order and record that figure. The difference between gross price and payout is your real fee, whatever the components were called. Related: Selling on Multiple Platforms

Shipping needs its own two numbers: what the buyer paid toward shipping, if anything, and what the label actually cost you. Free shipping listings hide the second number inside the price and are the most common reason a sale looks fine and the payout disappoints. Add returns to the same habit. A returned and resold item has two rounds of fees and often two labels, and unless both are recorded against the SKU, its profit line is fiction. Reconcile against the platform payout reports once a month, which is frequent enough to catch a mistake while you still remember the order. Related: What should a reseller do when a returned item needs to go back up for sale everywhere?

Keeping the record alive while the item moves around

The fields that get skipped are the ones that change over time. Log the first list date, every price change, and any relist, because those three give you holding time and markdown history, which is how you learn whether your pricing is ambitious or your photography is weak. An item that sold in a week at full price and an item that sold in eight months after three cuts have very different stories, and if the record only shows the final price they look identical. Holding time is also the honest input to any decision about how much stock you can carry.

Fill the record in at intake, when the item is in your hands and the receipt is in your pocket, because retrospective cost entry becomes guesswork within a month. A spreadsheet is completely adequate up to a few hundred items and is easy to export later; the reason people move to inventory software is usually the linking of one SKU to several live listings rather than the accounting itself. Keep the underlying receipts and payout statements for as long as your records are useful to you, and take questions about tax treatment or the right reporting method to a qualified accountant, since those rules depend on your situation.