For 2020, my dependent son (college student) accidentally claimed personal exemption, so my return was rejected. Will I be able to e-file after he amends his return?

[xmasbaby0]

No.  You will not be able to e-file this year at all.   When kids do this (which they do all the time)  parents who are trying to file after the kid made this mistake have to print, sign and mail their tax returns.  Sorry....you do not need to wait for him to amend.  It will be 4-6 months before his amended return is processed.  And....if he said he cannot be claimed you and he will have to deal with repaying stimulus money he may receive wrongfully.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.

[ColeenD3]

Yes, beginning with 2019 federal tax returns, you can e-file your 1040X. He will have to pay back any amounts he was not entitled to, including any stimulus.

[xmasbaby0]

Let's be clear-----Your son is the one who has to amend his tax return.   When the 1040X is available -- should be by March 18 --- he can e-file the amended return.    Your own return that claims him as your dependent cannot be e-filed.  YOU are not amending---only your son is amending.   You will mail an original Form 1040.