Comprehensive Sickness Insurance (CSI) is insurance that will cover the cost of most of the medical treatment you may require whilst you are in the UK.
As a rule, EU citizens are allowed to reside in the UK, subject to exercising rights of residence (e.g. employment, self-employment or self-sufficiency).
For inactive EU citizens (not seeking work, not in employment or self-employment, e.g. as a student or as a self-sufficient person), they must have Comprehensive Sickness Insurance to cover themselves and any dependent against all health risks in the UK (Article 7 Directive 2004/38)
Comprehensive Sickness Insurance
The NHS cover is not comprehensive cover (so held the Court of Appeals in Ahmad v Secretary of State for the Home Department  EWCA Civ 988);
A European Health Insurance Card (EHIC) issued by a member state other than the UK may be acceptable proof of comprehensive sickness insurance, subject to conditions. This is because the UK can recover the cost of healthcare against the member state issuing the EHIC, subject to conditions (under Regulation 883/04).
The other way to prove comprehensive sickness insurance is to provide evidence of private insurance with comprehensive cover. Directive 2004/38 does not define what “comprehensive” means. Helpful guidance is provided by the Home Office application form, which sets out that a private insurance policy will be comprehensive where it “covers the EU citizen (and the EU family members if applicable) for the majority of risks while in the UK”.
Given the difficulty in proving comprehensive sickness insurance, the advice is to provide private insurance with the most comprehensive and widest cover possible. Proof of the policy cover must be provided in with the application.
For further information on the notion of comprehensive sickness insurance, contact us at firstname.lastname@example.org.