My ex-wife has retained an attorney to negotiate an increase in child support. While I understand the motivation for its increase, I believe that two factors should be taken into account. I should note that I've always provided child support, including during a 4-year period where I was the custodial parent. First, she has the potential to earn much more (nearly double) than what she has claimed on her last tax return. Although her current spouse's income from his own business (also her current employment) should not be taken into account, it is clear that it contributes to her not earning to her potential. Secondly, based solely on her income and mine (excluding current spouses), it is clear that I would benefit more from claiming the tax exemption for our child. She is willing to negotiate a child support amount based on her earning potential but unwilling to allow me to claim the exemption, even though I've offered to offset her increased tax liability. Her unwillingness seems to be either an emotional response or based on her filing status (married filing jointly - including her spouse's income) making the exemption value greater for her. My Question: Some of this has now become a matter of principle. If I were to pursue this into court, would I have a reasonable chance of making a case on both factors described above?