Your sponsor must fill out the attached form. Both you and your sponsor must sign this form. •.Form I864, also known as the Affidavit of Support. This crucial piece of paperwork serves as a financial guarantee during the immigration process. I am providing this affidavit to verify my income as I have no other income documentation available to me. Instructions: Please provide one Certification of Sponsorship for each person helping fund your education. Edit, sign, and share sample letter affidavit form online. No need to install software, just go to DocHub, and sign up instantly and for free. The individual who signs the affidavit of support becomes the sponsor once the intending immigrant becomes a lawful permanent resident. This is a county specific form, informning.