ALWAYS CYA by having them fill in a W-9 ... they are free and simple. Never pay anyone a dime until you have this info ... you may think you will only pay them a small amount now but what happens if you do over that amount later in the year and you have no luck tracking them down in January for the needed info. If they will not fill in a W-9 for you then you don't need to use them ... it is a disaster waiting to happen.
https://www.irs.gov/pub/irs-pdf/fw9.pdf
