Assistance in the collection of taxes: cross-border enforcement and conservancy measures permitted under domestic law by competent authorities. Assistance in the collection of taxes allows a requested Contracting State, at the request of the competent authority of the requesting State, to accept and collect or to take conservancy measures with respect to a foreign 'revenue claim'-including taxes, interest, penalties and collection costs-by applying its own laws and procedures as if the claim were its own, subject to domestic law, public policy exceptions, proportionality of administrative burden, and the exclusive jurisdiction of the requesting State over disputes on existence, validity or amount.