@JLance1111 - You've tagged on to an old question about a totally different topic. That greatly limits the amount of experts who will see your question. You should ask a new question.
That said, the answer to your question is simple (although the explanation isn't): You cannot claim your daughter, unless the ex gives you permission on IRS form 8332. Even if a divorce decree, dated after 2008, gives the non-custodial parent the right to claim the child, he must still get form 8332 from the custodial parent. A properly worded decree should require her to provide that form. https://www.irs.gov/pub/irs-pdf/f8332.pdf
The IRS will not honor a divorce decree that says you can claim your daughter. they go by their own rules, which says the dependent goes to the custodial parent, regardless of the amount of child support. The IRS goes by physical custody, not legal custody.
Furthermore, for tax purposes, there is no such thing as joint custody, regardless of what your legal agreement says. The requirement, to be custodial parent, is that the child live with you MORE than 50% of the time. One of you has to be the custodial parent and the other the non-custodial parent. The IRS goes by physical custody, not legal custody.
Yes, the IRS expects you to count the numbers of nights the child sleeps at each parent's home. It is allowed for you to arrange the children's schedules so that one child spends more than half the year with the father while the other spends more than half with the mother. Then you are each the custodial parent of one child.
It is allowed for you to arrange the children's schedules so that the child spends more than half the year with the father one year and more than half with the mother the next year so that you are each the custodial parent in the year you claim the child, so that you can claim full benefits.
There is a way to split the tax benefits. For future negotiations with the other parent (and maybe even for this year) the following info may be of use:
There is a special rule in the case of divorced & separated (including never married) parents. When the non-custodial parent is claiming the child as a dependent/exemption/child tax credit; the custodial parent is still allowed to claim the same child for Earned Income Credit, Head of Household filing status, and day care credit. This "splitting of the child" is not available to parents who lived together at any time during the last 6 months of the year; then only one of you can claim the child for any tax reasons. The tax benefits may not be split in any other manner.
Note in particular that the non-custodial parent can never claim the Earned Income Credit, Head of Household filing status or the day care credit, based on that child, even when the custodial parent has released the dependency to him.
So, it's good idea to let the other parent know that you will be claiming those items, as many first time divorced parents are not aware of this rule and may try to claim those items, which will cause the IRS to send out letters.
Ref: https://www.irs.gov/publications/p17#en_US_2017_publink1000170897
Scroll down to "Children of divorced or separated parents (or parents who live apart)"
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Q. "Second question is does any of this matter if my daughter made more than $4200 from her part time job?"
A. Her income doesn't matter if she is under 19 (or under 24 if a full time student). There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, a relationship test, student status, and residence test. Only a QC qualifies a taxpayer for the Earned Income Credit and the Child Tax Credit.
