Will I be able to amend my return and file jointly with my wife if my return has already been accepted by state and federal?

[DDollar · Accepted solution]

Yes.  According to the IRS:

You can change your filing status from a separate return to a joint return by filing an amended return using Form 1040X.

You generally can change to a joint return any time within 3 years from the due date of the separate return or returns. This doesn't include any extensions. A separate return includes a return filed by you or your spouse claiming married filing separately, single, or head of household filing status.

Once you file a joint return, you can't choose to file separate returns for that year after the due date of the return.