The government issues Social Security numbers to all children born in the U.S. Your SSN is a nine-digit unique identifier – no two people have the same one. If you forget your SSN and you can't find your Social Security card, you can take measures to retrieve it.
You must have a SSN to get a job and to collect Social Security benefits, and it's important to protect your number to safeguard your identity.
Check Old Documents
Locate your previously filed income tax returns. The Internal Revenue Service requires that you include your SSN when filing returns, so your SSN should be on them. You can also look for W-2s, 1099s or other tax forms that have been forwarded to you. Each tax form issued to you includes your SSN because your SSN is the identifying number that the IRS uses to determine who you are and who received payment.
As a Last Resort
Visit your local Social Security office. Explain to the agent assisting you that you have forgotten your SSN. But be prepared to provide a certified copy of your birth certificate and your driver's license or other government issued form of photo ID. If your name is different than that listed on your birth certificate, you'll also need your marriage certificate, divorce decree or a court order changing your name.
Order a Replacement Card
If you have located your SSN but still need a replacement card, visit the Social Security Administration website to order a new one. To order a card using a My Social Security Online account, you cannot request a name change and must be over the age of 18. You must also have a driver's license or state identification card from a list of eligible states. Visit https://www.ssa.gov/ssnumber/ to see if your state is included. If you cannot fill out the application online, gather the required documentation and stop by your local Social Security Office or mail an application.
Read More: How to Order a Replacement Social Security Card Online