@Johnnie78
you said “spouse.“ Is this your current spouse or an ex-spouse? Are you divorced, or just separated? You also said the children are not “his.“ There are a couple of things you need to know.
In the case of stepchildren, a stepparent has the same legal right to claim a child as a dependent as a biological parent, and this relationship is maintained even after divorce. Under IRS regulations, once a stepparent, always a stepparent. This means that the ability to claim a child as a dependent is based on the usual rules of residency and support, and is not eliminated by a divorce or separation. If you have a biological child, but that biological child lived more than half the year with their stepparent, the stepparent can claim them as a dependent, even if you are divorced.
Secondly, there are several tiebreaker rules that may apply in the case of parents who are separated but not yet divorced. For example, if you lived together with the other parent for all of 2020, and separated or were divorced in the beginning of 2021, then both parents have the same right to claim the children as dependents because both parents lived with the children “more than half the year”. In this case, the tiebreakers apply.
The first tiebreaker is which parent did the children live with the most number of nights. For example, if you lived together in all of 2020 and separated in December, then you might have had custody 365 nights and the other parent had custody 335 nights. Although both parents have the right to claim the child as a dependent because both parents had custody more than half the year, if there is a disagreement, the tiebreaker will go to you for having the greater number of nights.
If the number of nights of custody is exactly equal, the second tiebreaker is taxable income. For example, if you, the other parent, and the children all lived together for 2020, then you and the other parent have custody an equal number of nights. In that case, if you disagree on who may claim the child as a dependent, the tiebreaker goes to the parent with the higher gross taxable income.
As stated before, if you can’t e-file because the other parent claimed a child that you believe you should claim, you will have to print your return and file by mail. Be prepared to send proof to the IRS of where the children lived the greater number of nights and be prepared to prove any of the other conditions required to claim a dependent. Carefully review IRS publications 501 and 504. Don’t send proof with your tax return, but have it on hand for when the IRS begins their investigation in the future.
