Here's the bottom line. The IRS has their own rules for determining who can claim the dependent in the case of divorced or separated parents. Your court order or decree really means nothing to the IRS since only a federal judge can override the IRS rules. Since federal judges don't deal with custody cases, that's never gonna happen. The basic qualifying child dependent rules are at <a rel="nofollow" target="_blank" href="
https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/qualifying-child-rules">...>
xmasbaby0 already covered the IRS Form 8332 which a lower court judge can order the custodial parent to sign and hold them in contempt of court if they don't sign it. But until the custodial parent has signed the 8332, the non-custodial parent just flat out can not claim the child. The IRS will not get involved in such legal proceedings either.
