5 CFR § 1655.16 - Reamortization.
(a) When a participant's pay cycle changes for any reason, he or she must notify the TSP record keeper of the change in the form and manner prescribed by the TSP record keeper. Upon notification, the participant's loan will be reamortized to adjust the scheduled payment to an equivalent amount in the new pay cycle. If the new pay cycle results in fewer payments per year and the participant does not reamortize the loan, the loan may be declared a deemed distribution pursuant to § 1655.15(a)(1).
(b) Upon reamortization, the outstanding principal balance remains the same. Any accrued interest is paid off first before payments are applied to principal and current interest.
(c) The interest rate on a reamortized loan will be the same as the interest rate on the original loan.