Collection assistance requires final determination and documentation, with collected taxes forwarded and limited by public policy.

Article 28 requires the requesting State's Competent Authority to certify that a revenue claim is finally determined and that domestic recovery remedies are exhausted, and to provide an official copy of the tax notice; collected amounts are forwarded to the requesting Competent Authority with possible reimbursement for agreed costs, subject to refusal of measures contrary to the executing State's public policy.

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