If you plan on making eBay efforts a tax-deductible business, one of the wisest things you should do is to separate your eBay business income and expenses from your personal accounts. Don't pay business expenses with a personal check or credit card, and don't deposit business income into your household checking account along with a spouse’s salary, tax refunds, client reimbursements, inheritances, lottery winnings, and heaven knows what else. Here is why it matters:
If you have a joint account with anyone other than a co-owner in your eBay business, that person could be dragged into a business audit.
If you have a joint account with anyone other than a co-owner in your eBay business, that person will also have access to all of your business funds. That could be a problem if, for example, you have to pay a large bill for new inventory on the same day that your joint account holder decides to make a major purchase for your household.
If you run your eBay business under a name other than your own legal name, you might not be able to deposit payments made out to your business in your personal account.
You’ll have a much harder time figuring your business deductions for interest, banking fees, and so on, because you’ll have to separate out the costs attributable to personal purchases.
Even if you have to pay a bit extra to open more accounts, having separate business accounts will simplify your bookkeeping life greatly. At the very least, open a business checking account. And if you can’t find a no-fee business credit card, simply use one of your personal credit cards just for business — that way, you’ll have no trouble calculating your interest deduction.