According to this article, there are three different ways to apply for a Social Security award letter, or a benefits verification letter (also known as a proof of income letter). These are formal government documents; the former confirms you’ve been approved for some form of benefits, while the latter specifies the benefits you receive from Social Security and related programs. The application process lets you request a letter by several methods:

• In Person — Individuals can request a copy of their award letter in person. To do this, simply look up an office close by and visit during business hours. However, it is important to remember that offices near you may have restricted access or be unavailable due to the pandemic.
• Online — The Social Security Administration prefers to work online; because of this, one of the easiest ways to apply for a benefits letter is through the SSA’s online account. Plus, there has been a lot of work done to improve the website, making it easier than ever to navigate.
• Over The Phone — A final way individuals can request benefit letters is by calling the SSA at 1-800-772-1213.

These letters can be useful in dealing with financial, government and other institutions, serving as an approval of benefits, and proof of income for taxes, loans, or other ventures that may require it.