As for 2016 Income Tax Return, I forgot to claim tax credit for the tax I paid against my retirement income from Japan. What can I do?

[tsakurai15]

How can I revise my Tax Return submitted yesterday?

[LinaJ2018 · Accepted solution]

If you have already e-filed, wait until your return is accepted or rejected by IRS / the state.

                -If your return is rejected, add your new information (along with anything else that needs to be corrected) and then re-submit your return.  See  Fix a reject

                -If your return has been accepted- you cannot change the information. Instead, you have to amend a return.   See instructions below.

IRS does not allow e-file for amendment,  you will need to submit the amendment forms with related supporting documents by mail. (Follow instructions through the step-by-step interview questions in the program)

If your original return generates a refund, you should wait until your original refund arrives before you file your amendment. You can cash your check, but you still should wait until your current tax return is resolved.  Note that if you see " Do Not File" watermark on your Form, this means your original return is either still pending or forms are not finalized yet.

https://ttlc.intuit.com/replies/5114064

As you are going through the amendment process, 

-On-screen  What do you need to change on your return?

-Scroll down to Deductions and Credits 

-Next screen, scroll down to Estimates and Other Taxes Paid / Foreign taxes, select Start