must I switch to reusable packaging by law

Switching to reusable is not a general requirement

No, there is no general obligation to switch to reusable packaging. The PPWR does not require that every package becomes reusable; what does apply are requirements regarding how much empty space a package may contain and, for plastic packaging, the share of recycled content processed in it. For a portion of transport packaging, specific reuse and deposit schemes exist, but that is different from a broad switching obligation that would apply to all packaging types and all businesses.

What matters more often in practice is reducing empty space in boxes and increasing the share of recycled material in plastic packaging. This particularly affects businesses that assemble transport packaging: the less air in the box, the sooner compliance with the empty space ratio is achieved. Whether something is a sales packaging or transport packaging makes a difference to which specific rules apply — this distinction is detailed in the difference between sales packaging and transport packaging. For box size itself, there is a direct link with the way a shipping box is filled and packed, something that becomes concrete when determining whether a box is too large or too heavy.

Where this follows from: Article 24 and Article 7

Article 24 of Regulation (EU) 2025/40 governs the empty space ratio: the requirement that packages do not contain unnecessarily much empty space, which mainly affects the way transport packaging is dimensioned, not the choice between single-use and reusable. Article 7 of the same regulation governs the mandatory share of recycled content in plastic packaging, which is a different type of requirement than a reuse obligation. Both articles thus say something about the composition and dimensioning of packages, but neither directly requires a switch to reusable packaging. Because the PPWR is a regulation, these two requirements apply substantively the same in every Member State; what does vary per country are the registers and supervisory practice surrounding packaging in general, but that does not affect the question of reusability as such. For the broader background on when the PPWR exactly applies and what the regulation primarily governs, the PPWR and the entry into force date provides an overview.