The Social Security Administration encourages everyone not to carry their Social Security cards every day. The best way to “guard your card” is to keep it in a safe place and only share when required. In most cases, just knowing the number should be enough.
Be careful about sharing your number when asked for it. You should always ask why your number is needed, how it will be used, and what will happen if you refuse. Also, don’t carry documents that display your number.
Source: Social Security Administration