(35)Some Member States are taking action to encourage packaging recyclability through modulation of extended producer responsibility fees. Such initiatives taken at the national level can create regulatory uncertainty for economic operators, in particular those that supply packaging in several Member States. At the same time, the modulation of extended producer responsibility fees is an effective economic instrument to incentivise more sustainable packaging design leading to more easily recyclable packaging while improving the functioning of the internal market. It is therefore necessary to harmonise criteria for the modulation of extended producer responsibility fees based on the recyclability performance grade obtained through the recyclability assessment, while not setting the actual amounts of such fees. As the criteria should be related to the criteria on packaging recyclability, it is appropriate to empower the Commission to adopt such harmonised criteria at the same time as establishing the detailed design for recycling criteria per packaging category.