Is CSI required by all EU citizens applying for British Citizenship or self-sufficient and students only?
You do not need CSI if you can evidence you were a worker or self-employed for your qualifying period.
However, even if the citizenship application asks you for 5 years of evidence in the first instance, there are cases where caseworkers check further in your history in the UK.
The Home Office can also apply discretion on your case, for instance if you had some gaps in your record.
If you are in doubt about your status in the past, it is a good idea to seek immigration advice on your particular application.
There are many organisations and individuals providing advice on citizenship. In the UK, all immigration advice is regulated, so please make sure you go to someone who is qualified to give you advice on this area of law. On the ILPA website, you can find a directory of members to find an immigration advisor near your area: https://ilpa.org.uk.
Note: this question, like other FAQs on Comprehensive Sickness Insurance (CSI), relates to applications for British citizenship, when considering whether periods of past residence were lawful. the3million’s Young Europeans have published a very useful document on key Citizenship facts which you can find here: http://www.t3m.org.uk/t3m_YE_KeyCitizenshipFacts.
CSI is not required to apply for pre-settled or settled status under the EU Settlement Scheme. Also, once pre-settled or settled status has been granted, you are lawfully resident, and you do not need CSI.