Here is a comprehensive list of documents that can serve as valid proof of Social Security Number:
Social Security Card
Paystub (must be within the last 90 days)
W-2 (up to 3 years prior)
1099 (last 2 years). Any type of 1099 will suffice
In cases where none of the above are available, the client can fill out an IRS Form W-9 in their place.
Ensuring that your proof of identification is current and in line with the specific requirements of the institution or agency you are dealing with is essential.