Typically, if you're talking about a band, they would have reserve lands or other lands. If you're talking about a group post-treaty, they'll have settlement lands, which could extend beyond the traditional reserve lands. Tax, when an indigenous government imposes it, would apply on those lands.
Typically, under the frameworks we have, it applies to both members of the community and non-members. For example, with the FNGST, both indigenous community members and non-members would pay if they were making a purchase of a good or a service on the lands.