(a) For a period of disability. To establish a period of disability, you must have disability insured status in the quarter in which you become disabled or in a later quarter in which you are disabled.
(b) For disability insurance benefits.
(1) To become entitled to disability insurance benefits, you must have disability insured status in the first full month that you are disabled as described in § 404.1501(a), or if later -
(i) The 17th month (if you have to serve a waiting period described in § 404.315(d)) before the month in which you file an application for disability insurance benefits; or
(ii) The 12th month (if you do not have to serve a waiting period) before the month in which you file an application for disability insurance benefits.
(2) If you do not have disability insured status in a month specified in paragraph (b)(1) of this section, you will be insured for disability insurance benefits beginning with the first month after that month in which you do meet the insured status requirement and you also meet all other requirements for disability insurance benefits described in § 404.315.