Much confusion surrounds the need to submit I751 affidavits and how to write them. We explain and provide an I-751 affidavit sample.Completing and signing Form I-864 makes you the sponsor. Use our I130 affidavit sample and tips to create a strong affidavit for your spouse. Include these key points and avoid common mistakes. The letter should also include a sentence saying that everything the affiant states in the letter is true. 1. Talk to the person immigrating to the US. The person for whom you write an affidavit should be someone you know very well. I am currently detained in the custody of the U.S. Immigration and Naturalization Service at the York County Prison in York, Pennsylvania. 5. The letter should also include a sentence saying that everything the affiant states in the letter is true.