This question is somewhat related to (perhaps broader than) my previous Make [welfare] a tag synonym of [social-welfare]. It may also be related to the pensions tag.
In this case, the question is about social security, which is a rather ambiguous term. According to Wikipedia:
Terminology in this area is somewhat different in the United States from in the rest of the English-speaking world. The general term for an action program in support of the well being of poor people in the United States is welfare program, and the general term for all such programs is simply welfare. In American society, the term welfare arguably has negative connotations.
In the United States, the term Social Security refers to the US social insurance program for all retired and disabled people. Elsewhere the term is used in a much broader sense, referring to the economic security society offers when people are faced with certain risks.
The current social-security is limited to the US definition. I think usage should be clarified more in the tag description and usage info. Given the large number of different benefits (e.g. see this list for the UK), it makes sense to have a meta post (this one?) that acts as a usage guide for correctly tagging such questions.
The primary goal of this question is to get an idea of how welfare / social-security questions should be tagged. Ideally, I think, it's kept simple with not too many tags but enough tags to get useful results when searching for similar questions.
For example, it makes sense for old-age and disability benefits to be tagged the same in the US, but not so for other countries. We could decide to tag them all the same, but then you're left with the ambiguity of different countries using the same name for different things.
Different programs / subjects that could be tagged differently but may not be entirely clear now (some are clear but added for completeness):
US social security program for old-age and disabled people
non-US program for disabled people (e.g. disability living allowance in the UK)
non-US old-age benefits
How should these subjects be tagged on this site?
Please indicate in your answer how these subjects should be tagged. Feel free to suggest more subjects that may be asked about on this site, are not obvious and should be added to the list.