Please see the
TurboTax FAQ "
How to
amend (change or correct) a return you already filed
," below, for
instructions on how to amend your previously-filed joint return.
https://ttlc.intuit.com/replies/3288565
Be aware, though,
that there's a deadline -- once you've filed a Married Filing Joint tax return,
you can't amend your filing status after the April 15th filing deadline.
