Classification on 4804520010 requires that the paperboard be manufactured and presented as base stock specifically for milk cartons or similar liquid packaging — typically evidenced by mill specifications referencing liquid packaging performance standards (barrier compatibility, heat-seal properties, or FDA-compliant coatings applied downstream). General packaging base stock lacking those liquid-packaging specifications would fall to 4804520040. Purchase orders and mill data sheets describing the intended end-use are the key supporting documents.

Both thresholds must be independently verified for each shipment. Mill certificates should state the grammage on a certified dry-weight basis and specify the pulp furnish composition confirming more than 95% chemical wood fiber. When sourcing from multiple origins, importers should standardize the documentation request to include both data points, as a board meeting one threshold but not the other will fall to a different heading — 480449 if fiber purity is insufficient, or 480452 if weight is below 225 g/m².