The FDIC bank insurance covers each depositor for an amount of $250,000.00 each in the bank account.
So if you have a joint bank account with your spouse then the FDIC usually sees that as two different people being depositors even in the same bank account.
So for example if the joint bank account had $500,000.00 in the bank account then the FDIC will usually insure the full $500,000.00
But that would mean that $250,000.00 of the bank account would be insured to one depositor and the other $250,000.00 would be insured to the other depositor.
So if you have $500,000.00 in one bank account as a joint bank account then that whole $500,000.00 would be insured by the FDIC.
However if the bank account is not a joint bank account then only $250,000.00 of that money would be guaranteed and insured.