20 C.F.R. § 416.1100
You are eligible for supplemental security income (SSI) benefits if you are an aged, blind, or disabled person who meets the requirements described in subpart B and who has limited income and resources. Thus, the amount of income you have is a major factor in deciding whether you are eligible for SSI benefits and the amount of your benefit. We count income on a monthly basis. Generally, the more income you have the less your benefit will be. If you have too much income, you are not eligible for a benefit. However, we do not count all of your income to determine your eligibility and benefit amount. We explain in the following sections how we treat your income for the SSI program. These rules apply to the Federal benefit and to any optional State supplement paid by us on behalf of a State (§ 416.2025 ) except as noted in subpart T and in the Federal-State agreements with individual States. While this subpart explains how we count income, subpart D of these regulations explains how we determine your benefits, including the provision that we generally use countable income in a prior month to determine how much your benefit amount will be for a month in which you are eligible (§ 416.420 ).
20 C.F.R. §416.1100