In 2026, taking milk through customs depends heavily on the origin, destination, and state of the milk. For international travel, most countries (especially the US, UK, and EU) have strict biosafety laws prohibiting the entry of liquid cow's milk from "unapproved" regions to prevent the spread of diseases like Foot-and-Mouth Disease. However, an exception is almost universally made for infant formula or breast milk; the TSA and international equivalents allow these in "reasonable quantities" in carry-on bags, even if they exceed 3.4oz. For standard dairy, "shelf-stable" or powdered milk is generally safer to bring through customs than fresh liquid. If you are crossing a land border, such as between the US and Canada, fresh milk is typically allowed for personal use in limited quantities. A high-value "pro-tip" for 2026 is to always declare any dairy products on your customs form; failure to declare a small carton of milk can lead to "Global Entry" revocation and fines up to $500, even if the milk itself was technically legal.