Many resellers only think about taxes when the marketplace sends a summary or their preparer asks for totals. That is usually when the missed deductions show up. The fix is not a bigger spreadsheet. It is a repeatable checklist and cleaner bookkeeping during the year.
This list is not tax advice for every business type, but it is a strong starting point for the categories resellers most often forget to track. Use it as an operating checklist and confirm the final treatment with your tax preparer.
Selling costs
- Marketplace fees, promoted listing spend, and payment processing fees
- Refund-related fees you absorb as part of selling
- Packaging materials such as boxes, tape, labels, and mailers
Logistics costs
- Postage, shipping labels, insurance, and signature confirmation
- Mileage for sourcing trips, post office runs, and local inventory pickups
- Travel tied directly to sourcing or inventory management
Operating costs
- Storage units, shelving, bins, and workspace organization supplies
- Software subscriptions for bookkeeping, inventory, and repricing
- Business-use share of phone, internet, and home office expenses
The real risk is not the deduction itself
The bigger issue is usually documentation. If you cannot tie a deduction back to a clean category, a receipt, or a business reason, it turns into a year-end scramble and your confidence drops fast.
That is why sellers who switch to a bookkeeping workflow early often save more time than money first. You stop rebuilding the same evidence trail every quarter.