If your state charges sales tax and you are attending storage auctions in order to resell goods for profit, you may want to consider applying for a Resale License/Certificate. You will have to go to your state’s tax department to get a sales tax ID number and application form, or you can usually fill one out online.
Make sure you read the requirements and procedures for obtaining a tax ID in your state. Most states vary, but usually you are required to files your business income taxes quarterly. If storage auctions are something you do just as a hobby right now, say for example you only attended one auction in the last two months, then you should consider holding off on the tax license until you are doing it more frequently. If storage hunting is your full time job, and you have an eBay shop or regularly attend flea markets, however, you should definitely have a tax ID for your state. The last thing you need is someone trying to pin you with tax evasion!
Below is a link to The Sales Tax Clearing House, a great site that shows you each state’s sales tax rate as well as the website through which you would apply for tax exemption within your state. Look through the FAQs and requirements for your state, and make sure you fully understand what you’re getting yourself into before you apply.