Question: Which Affidavit of Support form should I use to sponsor for a green card?
Answer: Form I-864 is usually used for green card petitions, and Form I-134 is used for non-immigrant petitions. Thus, if you were sponsoring your fiancé to come to the U.S. for the purpose to getting married, you will need to submit Form I-134 because K1 is a non-immigrant petition. On the other hand, when you and your fiancé get married, and you later file for his petition for a green card, you will submit Form I-864 because you are now filing for a permanent resident petition. Also, Diversity Visa lottery winners and returning residents will fill I-134 and not Form I-864.