To clarify the terminology and some background that a non-US person would not normally know:
TIN = Tax ID number
EIN = Employer ID number
SSN = Social Security Number
ITIN = Individual TIN
- TIN=EIN. People use them interchangeably, though they really should not. The term TIN refers to how you identify your company or yourself to the federal government.
If you have a corporation, the EIN is given to you by the US Federal Government's IRS (Internal Revenue Service, the Federal tax collector).
If you are not a corporation, you use your SSN as your identifier to the IRS.
The EIN is given to a corporate entity. It is the equivalent of a social security number for corporations.
the SSN is the closest thing we have in the US to a national identity card. It is used for all personal (non-corporate) identification purposes.
Using the SSN for tax identification causes a problem, since only people born in the US and legal immigrants have the number (in other words, people allowed to work in the US). If you are not allowed to work in the US, you do not have a TIN, and that causes problems as is your case, since you do not need to work in the US, but you do need to pay taxes due to your business activity (which is not illegal; it is not illegal for a foreigner to open a business here, it's illegal to work here only [The sense of this is a debate for a later time]).
The ITIN is given by the IRS to individuals who, though they are not allowed to work in the country, still have to report earnings/profits to the IRS. This number has the same format as the SSN, though it would be detected as an invalid SSN (SSN's can be decoded, that's also a topic for another day). Anyway, suffice it to say that without ITINs, people have to resort to much more shady things such as sharing someone else's SSN, and that really causes problems in the long term for everyone. Bottom line: You can get a ITIN from the IRS if you ask for it, no matter where you are from.
So much for tax ID numbers :)
About sales permits: Wholesalers ask you for this because we have a sales tax structure. It is not a VAT (Value added tax). What that means is that if you buy merchandise for resale, you do not pay tax on it. You, as the final seller, pay zero sales tax on your mechandise, and you collect the full sales tax from whom you sell to (that does not have a reseller ID). So you have to pay sales tax based on your sales. This is different from a VAT structure where you pay sales tax at purchase time regardless of whether or not you will resell the merchandise.
The wholesaler that sells to you will report that they sold the goods to you and did not charge you sales tax, because you are a reseller. They need to report your reseller permit number to justify to the authorities why they did not charge you sales tax. This is why the number is necessary. In most states (if not all) you do not need to be a corporation (ie, have an EIN) to have a reseller ID number. You can be a sole proprietor (not have a corporate entity) and be a reseller at the same time.
Now, to make this even more complicated: There is no national sales tax here. The sales tax structure is set by your state. This means that you have a bunch of different sales tax rates and rules for collecting sales tax, depending on which state your company has a physical presence on. Almost. Some states have begun charging sales tax for any sales made to that state (regardless of where the seller is located). Or charging sales tax for sales of goods shipped out of state (which did not have to pay tax until recently.
It becomes a big mess.
Fortunately, this is stuff that many accountants (if not all) know. Instead of us making a bad effort to clarify things here, it would be a very good idea for you to get a hold of an accountant at your state and have the accountant tell you exactly what you need to know about sales taxes for your state. Even if we could give you an accurate picture of how to do it here, it would vary by state.
Anyone, please feel free to correct anything that I might have explained wrong here.