In classical Tibetan many verbs have up to four different root forms. Spoken Tibetan makes indiscriminate use of verb stem forms that correspond to the “future” and the “present” in Literary Tibetan, and at the most only distinguishes between two tenses: the past and the present-future. While some verbs also have a distinctive imperative stem, in most cases this stem resembles either the present-future or the past. Very often, the verb is quite simply invariable.

The large number of invariable verbs means that inflection is practically redundant in the spoken language. Tenses are formed by using a system of auxiliaries.

For more information, see the entry on verb inflection in the appendices to this Reference Grammar.