20 C.F.R. § 416.503

If you receive an SSI benefit that does not include a State supplement the minimum monthly SSI benefit amount payable is $1. When an SSI benefit amount of less than $1 is payable, the benefit amount will be increased to $1. If you receive an SSI benefit that does include a State supplement and the SSI benefit amount is less than $1 but when added to the State supplement exceeds $1, the SSI benefit amount will not be increased to $1. Rather, we pay the actual amount of the SSI benefit plus the State supplement.