Article 37 establishes the statute of limitations for tax assessments. The Authority's right to assess tax expires five years after a return is filed, or ten years if no return was filed. For non-registered taxpayers, the ten-year period starts upon discovery of their activity. The limitation period is interrupted by a formal assessment notice, tax payment, or referral to the Tax Grievance Committee. This provision balances the Authority's need for audit time with the taxpayer's need for legal certainty, defining the specific timeframes after which past tax years are considered closed for further assessment.