When a company hires an individual as an independent contractor, the independent contractor will fill out a W-9 form using his or her Social Security Number (or SSN). When an employer hires a vendor, the vendor will use their Employer Identification Number (or EIN).

When a company hires an individual as an independent contractor, the independent contractor will fill out a W-9 form using his or her Social Security Number (or SSN). When an employer hires a vendor, the vendor will use their Employer Identification Number (or EIN).