turbo tax has this as guidance:
Business tax deductions for
ebay sellers
The only tax deductions you can use to reduce your gross
ebay sales income are those authorized by the IRS, but you'll have quite a few to choose from. Consider whether you qualify for:
Costs to purchase or fix up the items sold
Deductions for business use of your vehicle, either actual expenses or the standard mileage rate deduction, 56 cents a mile in 2021
Advertising expenses
Apportioned amount of phone and Internet charges related to your
ebay business
If you're still unsure if something is deductible, check out a more comprehensive list of common small business expenses.
Common small business deductions include costs for:
Automobiles
Bad debts
Depreciation
Employee compensation
Home office
Insurance
Interest
Legal and professional fees
Pension plans
Rent
Taxes
Travel, meals and entertainment
Other
Expenses you can't deduct
list of Expenses you can't deduct
Sorry, the news on write-offs isn't all good: Some business expenses are not deductible under any circumstances.
While the cost of entertainment at social, athletic, luncheon, sporting, airline and hotel clubs is deductible, the dues you pay to be a member are not, even if your membership is for business.
Federal income tax payments
Lobbying expenses
Penalties and fines you pay when you break the law
Political contributions