So I'm entering only the 2nd tax year since my divorce and I have a question for the group who have made it out.

Background: My ex is still unemployed 2 years after the divorce. As far as I know her only sources of income are the portion of my military retirement the court entitled her to, child support, and some SSDI. She may have some interest from her half of what little capital we had left. She was declared the custodial parent per the divorce decree and we exercise an extended standard possession order. According to my tax consultant none of the above, with the exception of the interest, is considered earned income and she more than likely will not need to file taxes. As the Non Custodial Parent, I was told to ask if she'd be willing to sign a tax form so that I can claim my child and reduce my taxes owed.

My question (finally): Is it common for the ex to ask for money to be paid in order to allow to you to claim your child? Or has anyone had a similar experience to this? How did you navigate it?

She asked and I was instantly offended. I explained that there's no money coming back. It just reduces what I owe. I feel like she's extorting me. Claiming the child is either her benefit or mine, and if she is unable to claim or utilize the benefit...I don't understand. I'm starting to believe this is probably common (I hope I'm wrong), but I felt like I was splashed with water when she asked. Can I get some perspective from the group please?