Can I amend my tax return to take off the EIC that I accidentally used by claiming my children, when my boyfriend is the one that claims our kids?

Come back at the end of March when the 1040-X amended return form will be ready. Since it will then take several months to process, BF will have to file his own return by mail.

You said you don't work, but you still filed a return.  Was that just to get the stimulus?  If you qualify to be your BF's dependent (even if he chooses not to claim you), you do not qualify for your own stimulus payments.  Or did you have some other type of income in 2020?

You can amend your return, but it will not help your BF to e-file this year.  The only way he can file now and claim the children is to print, sign and mail his return.   Your amended return will never "catch up" in the system for him to e-file this year.

The Form 1040X you need to amend will become available on March 25 (subject to change).   Not sure what you were doing---you could not get EIC if you had no income from working.

If you are an unmarried couple living together with your children, only one of you should enter the children on a tax return.  The other parent should not enter anything on their tax return about the children.

If you live together a dependent can only be on one tax return and uist not be on the other tax return at all..  The credits CANNOT be split.