So I let my Mother, my children's grandparents to claim my children because they did live with her while we remodeled our house. They were able to come back late spring when we got their new bedroom furniture in, which I can show that much. But she claimed them for the whole year this time without asking me because she says she needs the taxes and stimulus money for medical expenses. I only have proof starting when the kids went back to school and dental appointments. What can I do to fight this. She is refusing to change her return.
If your children lived with you for more than half of the year, and you provided more than half of their support; then you are eligible to claim them.
Here is some information about the requirements necessary to claim dependents: Claiming a Dependent
They IRS will not give you any information about who claimed your children, but if the children are your dependents your return will not be altered.