Because the child lived with you more than half the nights of the year, you are allowed to claim the child as a dependent without requiring any permission from a court or from the other parent. However, the child also lived more than half the nights of the year with the other parent, and therefore the other parent also has the right to claim the child as dependent. The first tiebreaker is which parent had custody the greater number of nights. If both parents claim the child as a dependent, the IRS will send a letter of investigation to each parent, and you will have to prove, by means of a diary or notes or other records that the child lived with you more nights than with the other parent. The IRS does not recognize custody orders and does not recognize “50-50“ custody, you have to actually count the number of nights where the child lived. In the case where the child lived exactly the same number of nights with each parent, the second tiebreaker will award the dependent to the parent with the higher income.
There is a series of special rules for claiming a dependent when the parents are divorced or separated and share custody, and those rules will apply for 2021 and the future, but those special rules do not apply for 2020 because each parent had custody more than half the nights of the year.
