Assistance in tax collection: mutual requests enable enforcement and conservatory measures under the requested State's domestic law. Contracting States may request mutual assistance to collect revenue claims, including taxes, interest, penalties and collection costs; the requested State shall collect enforceable claims or take conservatory measures in accordance with its domestic laws as if the claim were its own. Accepted claims receive no special time limits or priority in the requested State, and disputes over existence, validity or amount must be brought only before the authorities of the requesting State. Assistance may be refused where it conflicts with domestic law or public policy, where the requesting State has not pursued reasonable collection measures, or where the administrative burden is clearly disproportionate.