42 USC 12593 - Terms of service

(a) In general 
As a condition of receiving a national service education award under division D of this subchapter, a participant in an approved national service position shall be required to perform full- or part-time national service for at least one term of service specified in subsection (b) of this section.
(b) Term of service 

(1) Full-time service 
An individual performing full-time national service in an approved national service position shall agree to participate in the program sponsoring the position for not less than 1,700 hours during a period of not less than 9 months and not more than 1 year.
(2) Part-time service 
Except as provided in paragraph (3), an individual performing part-time national service in an approved national service position shall agree to participate in the program sponsoring the position for not less than 900 hours during a period of
(A) not more than 2 years; or
(B) not more than 3 years if the individual is enrolled in an institute[1] of higher education while preforming[2] all or a portion of the service.
(3) Reduction in hours of part-time service 
The Corporation may reduce the number of hours required to be served to successfully complete part-time national service to a level determined by the Corporation, except that any reduction in the required term of service shall include a corresponding reduction in the amount of any national service educational award that may be available under division D of this subchapter with regard to that service.
(c) Release from completing term of service 

(1) Release authorized 
A recipient of assistance under section 12571 of this title or a program sponsoring an approved national service position may release a participant from completing a term of service in the position
(A) for compelling personal circumstances as demonstrated by the participant; or
(B) for cause.
(2) Effect of release for compelling circumstances 
If a participant eligible for release under paragraph (1)(A) is serving in an approved national service position, the recipient of assistance under section 12571 of this title or a program sponsoring an approved national service position may elect
(A) to grant such release and provide to the participant that portion of the national service educational award corresponding to the portion of the term of service actually completed, as provided in section 12603 (c) of this title; or
(B) to permit the participant to temporarily suspend performance of the term of service for a period of up to 2 years (and such additional period as the Corporation may allow for extenuating circumstances) and, upon completion of such period, to allow return to the program with which the individual was serving in order to complete the remainder of the term of service and obtain the entire national service educational award.
(3) Effect of release for cause 
A participant released for cause may not receive any portion of the national service educational award.
[1] So in original. Probably should be “institution”.
[2] So in original. Probably should be “performing”.