I might have misspoken or not spoken clearly enough. Currently the tax commission works with first nation communities who are interested in putting in place a taxation regime. There's nothing to prevent them from already using their indigenous languages, as long as it's available as well in the language of the residents—the taxpayers—who are living in the community. Any first nation could put forward a tax regime that also offers it in their own language.
On November 5th, 2018. See this statement in context.