I receive a huge amount of money $5,000 in my checking account from out of nowhere! I recieve SSI every month, is it a mistake?

If you had retroactive benefits they are paid in three installments, six months apart. As you should very well know since SSI would have sent you notices about them. I do not understand why people ask questions they know the answer to as if they don't. And if you truly don't know you need a payee as it would seem you are incapable.

If the $5000 is not a retroactive SSI benefit then you are required, by law, to report it to social security since resources of $2000 (if single; $3000 if married) or more makes you ineligible for SSI. You are required to report changes in income, resources and living arrangements within ten days of the change by either calling 1-800-772-1213 or by visiting or writing your nearest social security office.

Source: I was a social security claims rep for 32 yrs.

Received it from WHOM/WHAT? It didn't come from "nowhere." Your account statements will indicate a payer.

Ask your bank where it came from. If it is a mistake, don't spend it because it will be taken back.

No, I have never had that happen to me, although I would love for it to happen.