34 C.F.R. § 303.21
(a) Infant or toddler with a disability means an individual under three years of age who needs early intervention services because the individual—
(1) Is experiencing a developmental delay, as measured by appropriate diagnostic instruments and procedures, in one or more of the following areas:
(2) Has a diagnosed physical or mental condition that—
(c) Infant or toddler with a disability may include, at a State's discretion, a child with a disability who is eligible for services under section 619 of the Act and who previously received services under this part until the child enters, or is eligible under State law to enter, kindergarten or elementary school, as appropriate, provided that any programs under this part must include—
(2) A written notification to parents of a child with a disability who is eligible for services under section 619 of the Act and who previously received services under this part of their rights and responsibilities in determining whether their child will continue to receive services under this part or participate in preschool programs under section 619 of the Act.
(Authority: 20 U.S.C. 1401(16), 1432(5))