A sworn affidavit is an optional document usually used when you have not enough other evidences of a good faith marriage. An affidavit is the weakest sort of evidence to be filed together with Form I-751. So please see our article “What should I send with Form I-751 to provide proof of a good faith marriage” to find out the full list of the supporting documents proving a bona fide marriage.
Affidavit is a written evidence, a personal declaration of facts, of your relationship in marriage provided by a third party. A personal affidavit becomes “sworn” when a declarant adds the “under penalty of perjury” words to the end of that document. Thus, affidavit is already a sworn statement by definition, so there is no need to have it sworn before a notary public. However, if you just want to feel reassured you may turn to a notary to attest the affidavit.
According to the Instructions for Petition to Remove Conditions on Residence, along with copies of documents indicating that the marriage upon which you were granted conditional status was entered in “good faith” you can additionally submit affidavits to establish this fact. Affidavits should be sworn to or affirmed by at least two people who have known both of you since your conditional residence was granted and have personal knowledge of your marriage and relationship. The original affidavit must be submitted and also contain the following information regarding the person making the affidavit: his/her full name and address; date and place of birth; relationship to you or your spouse; full information and complete details explaining how the person acquired his/her knowledge.