These Guidelines provide a structured framework for developing Standard Operating Procedures (SOPs) to support the effective enforcement of the Montreal Protocol. They offer practical templates and examples to assist Customs administrations in customizing SOPs to meet specific operational requirements, including legislative frameworks, clearly defined roles, and procedures for controlling Montreal Protocol–controlled substances, as well as related products and equipment. By applying these Guidelines, Customs administrations can strengthen compliance, enhance border management, and foster collaboration with key stakeholders, supporting effective regulatory implementation and alignment with Montreal Protocol obligations.