Currently, the Income Tax Act permits sharing of information relating to the national Canada child benefit supplement with provinces solely for the purposes of them being able to put in their benefit systems, where they might need that information in order to do so. The issue is that with the replacement of the former system of child benefits, those being the national child benefit supplement, the Canada child tax benefit, and the universal child care benefit, with the Canada child benefit in 2016, the information relating to the national child benefit supplement will no longer be available. It currently exists as a vestigial component of the Canada child benefit formula, although that is legislated to be removed. With the elimination of the national Canada child benefit supplement, information relating to that program will no longer be available. The provinces would still need information relating to federal child benefits for the purpose of their programs; so along with the shift from the NCBS to the Canada child benefit, the information to be provided shifted.
On April 24th, 2018. See this statement in context.