Did someone claim your child as a dependent? If someone else claimed your child as a dependent on their tax return, you should print sign and mail your own tax return that claims your child. Then the IRS will hand process your return and sort out who could have claimed the child.
The stimulus money was an advance on a credit you can get on your 2020 tax return. So----if you prepare a tax return claiming your children and it is rejected when you try to e-file, mail your return instead. "Now they're trying to do it again..." How do you know that? Do you know who claimed your child?
If your child was claimed fraudulently, the person who claimed the child may face repayment of any child-related credits they received for claiming the child PLUS penalties.
The stimulus check is an advance on a credit you can receive on your 2020 tax return. If something went wrong or you did not get the stimulus check this year, you can get it when you file your 2020 return in early 2021—if you are eligible.It will end up on line 30 of your 2020 Form 1040.