Except as provided in paragraph (2), funds provided under this subchapter, or subchapter I, may not be used to provide extended services to individuals under this subchapter or subchapter I.

Funds allotted under this subchapter, or subchapter I, and used for the provision of services under this subchapter to youth with the most significant disabilities pursuant to section 795h(d) of this title, may be used to provide extended services to youth with the most significant disabilities. Such extended services shall be available for a period not to exceed 4 years.