The phonetic forms of morphemes may undergo changes depending on the phonetic context they are situated in. These changes are more prominent in verbal structures. The present article investigates two processes of vowel elision and assimilation in Kalhori Kurdish subjunctive/imperative prefix. To this end, after collecting relevant data through interviewing 10 Kalhori Kurdish speakers living in Eslamabad-e Gharb, the alternating forms of this prefix were extracted, and the underlying form was obtained. The phonological changes were analyzed in Optimality Theory, with the phonological form as the input. The results from the collected data show that of the subjunctive/imperative morpheme /bə-/, three phonetic forms of [bə-], [b-], and [bu-] are obtained, with the last two formed by elision and assimilation processes, respectively; and for them to be formed, markedness constraints have to dominate faithfulness constraints. It was also revealed through the analyses that for explaining assimilation in Optimality Theory, the whole place of articulation must be targeted rather than the individual phonological features.