I am providing this affidavit to verify my income as I have no other income documentation available to me. CitizenPath has prepared a downloadable I751 affidavit sample that you can forward to friends who are willing to write a letter of support.Requests for Letters of Support must be submitted to the County six weeks prior to the date needed. For more information on the process, visit the website. I am competent to testify as to the matters set forth herein and if called as a witness would testify as set forth below. An affidavit or letter can be used to fill gaps, corroborate or support other evidence or explain shortcomings or weaknesses in a petition. Are we not considered self-employed? Private practice lawyers typically use this type of document for witnesses.