Any contributor to Surface magazine who is a US citizen must provide a completed W9 form. If you do not already have a W9 form, you may find one here.
If you are not a US citizen, you do NOT need to complete or submit a W9.
Shortly, a member of the Surface team will provide you with your specific use rights agreement, which will outline the terms of your assignment, and the conditions under which Surface may use and reproduce the content you provide.
Surface Magazine must have all applicable documentation prior to making payment for any contributor services.