Assistance in tax collection: mutual assistance enables cross border enforcement and conservancy subject to domestic law and public policy limits. Contracting States shall provide mutual assistance in the collection of taxes by accepting, at the request of a competent authority, revenue claims for collection or measures of conservancy and enforcing them under the assisting State's laws as if the claim were its own. 'Revenue claim' includes taxes, interest, administrative penalties and collection costs, provided taxation is consistent with the Convention. Assistance is limited by domestic law, public policy, disproportionate administrative burden, and the requirement that the requesting State first pursue reasonable domestic measures; disputes about the claim's existence, validity or amount remain within the requesting State's courts or bodies.