Nachiring, a language of the Khambu subgroup (―Kiranti‖, Trans-Himalayan a.k.a. Tibeto-Burman) spoken in eastern Nepal, transparently marks non-past tense (NPT) in the verbal morphology with the suffix -d(a). No such tense marking has been described so far for the other Khambu languages Kulung and Sampang. This article will argue that traces of a cognate morpheme have been preserved in Kulung. These traces are found in stem alternations on the one hand and in person agreement suffixes on the other hand. The parallels in form, distribution and syntagmatic arrangement prove these traces to be cognate with the Nachiring NPT -d(a) and that therefore a NPT morpheme *-da is reconstructible for proto-Khambu. The article also briefly points at possible traces of such a NPT marker in the third Khambu language Sampang and in the geographically adjacent language Koyi.