Wondering what in the world a, IRS (Internal Revenue Service) W9 Form is? First off it is one of the many forms provided by the Internal Revenue Service, AKA The IRS. This W9 Form is used by companies to request the important information they need from freelancers they have used in the tax year. Those freelancers will receive the W9 Form fill it in and send it back to the company that was requesting it. Please also note that the IRS (Internal Revenue Service) W9 Form does not get filed with the IRS (Internal Revenue Service), that is what the 1099 Form is used for.