Assistance in the collection of taxes permits states to enforce foreign tax claims under their own laws with defined limits. Assistance in collection allows Contracting States to accept and enforce or conserve revenue claims of the other State as if domestic, with 'revenue claim' encompassing taxes, interest, penalties and collection costs; such claims are collected or conserved under the requested State's laws, without conferring domestic priority or altering limitation rules, and assistance is subject to limits including conformity with domestic law, public policy, prior reasonable efforts by the requesting State, and proportionality of administrative burden.