Ebay income and taxes

I have a lot of things I want to sell on Ebay but have no receipts because the items were purchased a long time ago. How is Ebay income treated tax-wise? Can I just increase my 401k contribution amounts to defray the Ebay income and just kick the tax can down the road another few decades? That is what I think I will have to do. I’ll get the income from Ebay sales but delay taxes for a while.

If you’re selling stuff at a loss, there’s no income tax. If you’re making a profit, then you treat the profit as business income. Yes, you can contribute to a 401k (either through your regular job or via a solo 401k) if you qualify. But you’d still calculate and report the income now.