20 CFR §404.1503

1. (a)State agencies. State agencies make disability and blindness determinations for the Commissioner for most persons living in the State. State agencies make these disability and blindness determinations under regulations containing performance standards and other administrative requirements relating to the disability and blindness determination function. States have the option of turning the function over to the Federal Government if they no longer want to make disability determinations. Also, the Commissioner may take the function away from any State which has substantially failed to make disability and blindness determinations in accordance with these regulations. Subpart Q of this part contains the rules the States must follow in making disability and blindness determinations.
2. (b)Social Security Administration. The Social Security Administration will make disability and blindness determinations for—
   1. (1)Any person living in a State which is not making for the Commissioner any disability and blindness determinations or which is not making those determinations for the class of claimants to which that person belongs; and
   2. (2)Any person living outside the United States.
3. (c)What determinations are authorized. The Commissioner has authorized the State agencies and the Social Security Administration to make determinations about—
   1. (1)Whether you are disabled or blind;
   2. (2)The date your disability or blindness began; and
   3. (3)The date your disability or blindness stopped.
4. (d)Review of State Agency determinations. On review of a State agency determination or redetermination of disability or blindness we may find that—
   1. (1)You are, or are not, disabled or blind, regardless of what the State agency found;
   2. (2)Your disability or blindness began earlier or later than the date found by the State agency; and
   3. (3)Your disability or blindness stopped earlier or later than the date found by the State agency.