My wife and I divorced this year. We have agreed that she will claim our two youngest on her tax return and that I will claim our oldest on mine. She is considered the "custodial parent". So, I understand that she has the sole right to claim HoH, even if she is not claiming our oldest.
My question is this though, if I satisfy the requirement of my oldest staying the night at my house 50% of the year, could we both claim HoH? She claiming it with the two youngest and me claiming it with our oldest? I have searched a bit on this scenario and found nothing. My understanding is that regardless, if I have my oldest 50% of the nights, I have the right to claim HoH...regardless of who the custodial parent is. Is this correct? I could not find a scenario where both parents would be allowed to claim HoH...
If for example, I have my oldest 47% of the year, and my ex-wife does not claim her on her taxes, what is stopping me from claiming Head of Household anyway??
Two things here. First, determining who qualifies to claim the child as their dependent has to be clarified. Then determining if one can claim HOH is a totally separate determination that has nothing to do with claiming the child as a dependent really.
Now jjust to clarify for others reading this thread, the IRS does not care about any custody agreement you may or may not have. They have their own rules which must be followed when it comes to claiming dependents and qualifying to file as HOH. The reason any custody agreement is not relevant to your taxes is because the laws on this are federal laws, commonly referred to as "the IRS rules". But it's federal law all the same. The only legal authority that can override federal law is a federal judge. Since federal judges do not deal with child custody issues or even divorces, that's very unlikely to ever happen.
Now, per the IRS rules they define the custodial parent as the parent with whom the child lives with for more than 182 nights of the tax year. Temporary absences, such as hospital stays, sleepovers at a friends house, etc. count provided the child returns to the same household at the end of the temporary absence, as they one they left at the start of the absence. If the separation took place say for example, in Nov of the tax year, then the custodial parent is the parent with whom the child lived the most number of nights during the year. Now that's just the basics. There's other requirements too. But basically for your taxes, this determines who the IRS recognizes as the custodial parent, and therefore the parent with the right to claim the child as a dependent on their taxes.
Now for the parent's filing status, just because a parent qualifies as the custodial parent, does not mean they qualify to claim the filing status of HOH. The requirements to file HOH are clearly spelled out in IRS publication 501. The requirements are:
You paid more than half the cost of keeping up a home for the year.
A qualifying person lived with you in the home for more than half the year (except for temporary absences, such as school).
Now is your case, using the example you provided and not your actual situation, by the IRS rules you are not the custodial parent since the dependent lived in your house less than 182 nights or less than 50% of the time for the year. However, you can claim the dependent if the custodial parent signs an IRS form 8332 releasing their right to claim the dependent, to you.
Then going by the requirements for HOH which have noting to do with the fact you can legally claim the dependent as such on your return with a signed 8332 from the custodial parent, you may have met the first two requirements just fine. But since the dependent did not live with you in your home for more than half the year, you do not qualify to claim the HOH filing status.