(a) Under such regulations as the Secretary concerned may prescribe, and subject to the recommendations of a board of officers or a selection board under section 576 of this title, a permanent regular warrant officer who is eligible for retirement under any provision of law shall be retired under that law if his records and reports establish his unfitness or unsatisfactory performance of duty. If he is not eligible for retirement under any provision of law, but since the date when he accepted his original permanent appointment as a regular warrant officer he has at least three years of active service that could be credited to him under section 511 of the Career Compensation Act of 1949, as amended (70 Stat. 114), he shall, if eligible therefor, be separated with separation pay under section 1174 of this title or severance pay under section 286a of title 14, as appropriate. However, instead of being paid separation pay or severance pay he may be enlisted under section 515 of this title. If he does not have three years of such service, he shall be separated under section 1165 of this title.

(b) The Secretary concerned may defer, for not more than four months, the retirement or separation under subsection (a) of any warrant officer if, because of unavoidable circumstances, evaluation of his physical condition and determination of his entitlement to retirement or separation for physical disability require hospitalization or medical observation that cannot be completed before the date when he would otherwise be required to be retired or separated under this section.