If you have already filed your return, you'll need
to wait for your tax return to either be rejected or accepted, if it is rejected you can add any information that needs to be added/corrected, correct any other
errors on the return and resubmit it. If it is accepted, you will need to amend your return to include the additional information or make changes. You cannot e-file an amended return as this cannot be filed
electronically. The form is only filed on paper, so it will need to be
printed and filed by mail.
Please see the following TurboTax FAQ for instructions on how to amend your 2016 tax
return in TurboTax.
https://ttlc.intuit.com/replies/3288565