Zero rating is the practise of an ISP not counting the data used by a customer when using a service against their monthly data allowance. The common argument against this is that it harms competition. If an ISP incentivises its customers to use a particular companies' services then other companies in that market have reduced access to customers.
The EU net neutrality Regulation allow ISPs to do zero-rating in certain circumstances. The BEREC guidelines on the EU Net neutrality lay out those circumstances.
The Regulation does not preclude ISPs from setting a data cap on the IAS products
they offer end users. In some cases, ISPs may wish to include a “zero-rating” feature on an IAS with a data cap, under which access to specific services does not count towards the data cap.
The Regulation does not prohibit zero-rating outright. However, as the BEREC Guidelines note, IAS with zero-rating should be assessed closely by NRAs to ensure that they do not undermine the goals of the Regulation. The Guidelines recommend that such assessments should take into account:
i) the goals of the Regulation;
ii) the market positions of the ISP and Content and Application Providers (‘CAP’) involved;
iii) the effects on consumer and business customer end-user rights;
iv) the effects on CAP end-user rights; and,
v) the scale of the practice and presence of alternatives.
Examples of zero-rating in the UK
- EE zerorates Apple Music for 6 months for pay monthly customers
- Virgin Mobile zerorates Facebook Messenger, WhatsApp and Twitter on Pay Monthly plans 
- Three zerorates Netflix, TV Player, Deezer and Soundcloud for customers on plans that include over 4GB of data per month