Utah Code § 39A-5-304: Forfeiture of pay as sentence.

(1) When a lawful and approved sentence of a court includes a forfeiture of pay or allowances in addition to confinement that is not suspended or deferred, the forfeiture may apply to pay or allowances becoming due on or after the date the sentence is approved by the convening authority.

(2) A forfeiture may not extend to any pay or allowances received before that date.