Under the AIM Act and EPA's HFC allowance program, importers of HFC blends must hold sufficient consumption allowances for the HFC content of each shipment. Allowances are allocated annually and can be traded; importers without sufficient allowances cannot legally bring HFC mixtures into the US. Documentation of allowance transfers must accompany the entry.

The key distinction is whether the mixture contains any hydrogen-containing chlorofluorocarbon (HCFC) component. If it does and contains no CFCs, it falls in the HCFC group (382731–382739). If the mixture contains only hydrofluorocarbons—no chlorine-bearing ODS—it is classified in the HFC subheadings (382761–382769) based on the dominant HFC component by percentage. Verify the blend's composition certificate against the specific percentage thresholds in each subheading.