Is a "Tax I.D. number" just a SSN, or is it something different? If it's something I don't have, I'll need to figure out a workaround.
I'm guessing that they're looking for an incorporated EIN (Employer Identification Number), which would show them that you're a business. It is basically an SSN for a business. The format is slightly different from a regular SSN since it is written XX-XXXXXXX, so it still has nine digits, just separated differently. But their definition of "Tax I.D. Number" could be just referring to SSN, so I'd give them a call.