The Social Security Administration also issues another type of document, a benefit verification letter, which includes more details about your benefit and can serve as proof of your income from ...

One of those documents will be a “proof of funds” (POF) letter. This real estate paperwork ... already had your lender verify your source of income and the amount of money you have on hand.

A veteran proof of service letter serves as proof of honorable service in the uniformed services. The letter can be obtained through the upgraded eBenefits premium (free) account access.