34 CFR 690.67: Eligibility to receive additional Federal Pell Grant funds in an amount up to one-half of a Scheduled Award during a single award year.

An institution awards additional Federal Pell Grant funds up to one-half of a Scheduled Award to a student in an award year if the student is enrolled—

(a) In an eligible program leading to a bachelor's or associate's degree or other recognized educational credential, except as provided in 34 CFR part 668, subpart O, for students with intellectual disabilities, for one or more additional payment periods during the same award year that are not fully covered by the student's initial Federal Pell Grant Scheduled Award; and

(b) At least as a half-time student in the payment period(s) for which the student receives any portion of the additional Federal Pell Grant funds.