20 CFR 404.1690: Assumption when we make a finding of substantial failure.

(a) Notice to State. When we find that substantial failure exists, we will notify the State in writing that we will assume responsibility for performing the disability determination function from the State agency, whether the assumption will be partial or complete, and the date on which the assumption will be effective.

(b) Effective date of assumption. The date of any partial or complete assumption of the disability determination function from a State agency may not be earlier than 180 days after our finding of substantial failure, and not before compliance with the requirements of § 404.1692.