Section 435.540 - Definition of disability(a)Definition. The agency must use the same definition of disability as used under SSI, except that-(1) In determining the eligibility of individuals whose Medicaid eligibility is protected under §§ 435.130 through 435.134 , the agency must use the definition of disability that was used under the Medicaid plan in December 1973; and(2) The agency may use a more restrictive definition to determine eligibility under § 435.121 , if the definition is no more restrictive than that used under the Medicaid plan on January 1, 1972.(b)State plan requirements. The State plan must contain the definition of disability.