A Sales Tax ID is a number you obtain from your state and/or local government that allows you to charge sales tax whenever a buyer in your state, county and/or city purchases an item from you, even if it’s an online purchase.
It's not always required to get started with most suppliers but there are quite a few benefits of obtaining one. I'd recommend you check out a couple of blog posts we wrote on the topic to give you a better understanding:
If you are serious about establishing a business on eBay, in most US states, you'll need a Sales Tax ID. If you live outside of the US and the supplier requires a Sales Tax ID, you can provide the supplier with the closest equivalent to a Sales Tax ID for your country. For example, if you live in the UK or the EU, you will need to be a VAT registered trader so in place of a Sales Tax ID use your VAT ID. In Australia and New Zealand, you can use your GST number.
Alternatively, the wholesaler may want to see your business license/registration details. Below are guides to help you register your business:
Short URL to this FAQ: https://www.salehoo.com/u/icH5H