Capitalization doesn’t matter---even if one is technically correct, both are understood.
Kent Thornell 21, Studied at University of Northern Iowa, “Should "Social Security" be capitalized when referring a social security number or card in a sentence?,” https://englishlanguage1.quora.com/Should-Social-Security-be-capitalized-when-referring-a-social-security-number-or-card-in-a-sentence#:~:text=Should%20%22Social%20Security%22%20be%20capitalized,or%20card%20in%20a%20sentence%3F&text=Technically%20it%20should%20be%20capitalized,reading%20it%20would%20still%20understand%20.
Should "Social Security" be capitalized when referring a social security number or card in a sentence?
Technically it should be capitalized as it is a proper noun. However, it is often not in everyday writing because it’s easier to write in lower case and anyone reading it would still understand.