37 U.S. Code § 315 - Special pay: engineering and scientific career continuation pay
(a) In this section, the term “engineering or scientific duty” means service performed by an officer—
(2) that requires a skill designated (under regulations prescribed by the Secretary of Defense for the armed forces, by the Secretary of Commerce for the National Oceanic and Atmospheric Administration, or by the Secretary of Health and Human Services for the Public Health Service) as critical and as a skill in which there is a critical shortage of officers in the uniformed service concerned.
(b) Under regulations prescribed by the Secretary concerned, an officer of a  uniformed service who—
(4) has been certified by the Secretary concerned as having the technical qualifications for detail to engineering or scientific duty;
(5) has completed at least three but less than nineteen years of engineering or scientific duty as an officer; and
(6) executes a written agreement to remain on active duty for detail to engineering or scientific duty for at least one year, but not more than four years;
may, upon acceptance of the written agreement by the Secretary concerned, be paid, in addition to all other compensation to which the officer is entitled, an amount not to exceed $3,000 multiplied by the number of years, or monthly fraction thereof, of obligated service to which the officer agrees under the agreement. The total amount payable may be paid in a lump sum or in equal periodic installments, as determined by the Secretary concerned.
(c) An officer who, having entered into a written agreement under subsection (b) and having received all or part of a bonus under this section, does not complete the period of active duty as specified in the agreement shall be subject to the repayment provisions of section 303a (e) of this title.
 So in original. Probably should be “an”.
Source(Added Pub. L. 97–60, title I, § 120(a),Oct. 14, 1981, 95 Stat. 998; amended Pub. L. 99–145, title VI, § 637(a),Nov. 8, 1985, 99 Stat. 648; Pub. L. 100–26, § 8(e)(6),Apr. 21, 1987, 101 Stat. 286; Pub. L. 102–25, title VII, § 702(b)(1), (2), (c),Apr. 6, 1991, 105 Stat. 117; Pub. L. 109–163, div. A, title VI, § 687(b)(24),Jan. 6, 2006, 119 Stat. 3331.)
2006—Subsec. (c). Pub. L. 109–163amended subsec. (c) generally, substituting provisions referring to repayment provisions of section 303a (e) for specific provisions relating to refunds required when officer receives bonus but fails to complete agreed upon period of active duty.
1991—Subsec. (c). Pub. L. 102–25struck out “of this section” after “subsection (b)” in two places in par. (1) and struck out “of this subsection” after “paragraph (1)” in pars. (2) to (4) and after “paragraph (3)” in par. (2).
1987—Subsec. (a). Pub. L. 100–26inserted “the term” after “In this section,”.
1985—Subsec. (a). Pub. L. 99–145, § 637(a)(1), amended subsec. (a) generally. Prior to amendment, subsec. (a) read as follows: “In this section, the term ‘engineering or scientific duty’ means service performed by an officer that requires an engineering or science degree and that requires a skill designated under regulations prescribed by the Secretary of Defense as critical and as a skill in which there is a critical shortage of officers in the armed force concerned.”
Subsec. (b). Pub. L. 99–145, § 637(a)(2), in provision preceding par. (1), substituted “prescribed by the Secretary concerned” for “prescribed by the Secretary of Defense” and “officer of a uniformed service” for “officer of an armed force”.
Effective Date of 1985 Amendment
Pub. L. 99–145, title VI, § 637(b),Nov. 8, 1985, 99 Stat. 649, provided that: “The amendments made by subsection (a) [amending this section] shall take effect on October 1, 1985.”
For savings provision relating to payment or repayment of any bonus, incentive pay, special pay, or similar pay obligated to be paid before Apr. 1, 2006, under a provision of this section amended by section 687(b) ofPub. L. 109–163, see section 687(f) ofPub. L. 109–163, set out as a note under section 510 of Title 10, Armed Forces.