The aim of this contribution is to confront the perfective and imperfective paradigms of verbs and to formulate testing procedures that would allow for the determination of the aspectual status of the aspectual paradigm of a verb as reliably as possible. The main task is to find a way to detect the presence of the perfective paradigm in the set of forms of a biaspectual verb. Both paradigms were confronted from the perspective of: (1) which forms they contain; (2) the functioning of their forms under certain conditions; (3) the ability of their forms to accompany each other. The author presents methods for verifying the presence/absence of the perfective paradigm in the set of forms of the 'candidates for biaspectuality'. Two configurations evidence the presence of the perfective paradigm. First, the acceptability of the present tense in temporal clauses introduced by the conjunctions 'az' and 'nez', and second, the possibility of a double interpretation of a complex sentence with a perfective preterite in the main clause and the conjunction 'kdyz' and a preterite in the temporal clause. Subsequently, the author constructs an algorithm for determining whether a paradigm is imperfective or perfective or whether two homonymous paradigms coexist.