Subject to the limitations contained in paragraph (4), an individual who would have been entitled to a benefit under subsection (a), (b), (c), (d), (e), (f), (g), or (h) for any month after August 1950 had he filed application therefor prior to the end of such month shall be entitled to such benefit for such month if he files application therefor prior to—

(A) the end of the twelfth month immediately succeeding such month in any case where the individual (i) is filing application for a benefit under subsection (e) or (f), and satisfies paragraph (1)(B) of such subsection by reason of clause (ii) thereof, or (ii) is filing application for a benefit under subsection (b), (c), or (d) on the basis of the wages and self-employment income of a person entitled to disability insurance benefits, or

(B) the end of the sixth month immediately succeeding such month in any case where subparagraph (A) does not apply.

Any benefit under this subchapter for a month prior to the month in which application is filed shall be reduced, to any extent that may be necessary, so that it will not render erroneous any benefit which, before the filing of such application, the Commissioner of Social Security has certified for payment for such prior month.