Yesterday I re-did our taxes from last year to get a feel for whether it's cheaper to be married or single as of Dec. 31st. Surprise, but in our tax bracket there is still a hefty "marriage tax". Ha ha, we should have gotten divorced years ago.
Turbotax told me to file head of household. Being divorced appears to save both of us money on taxes, but saves me more as Wolfy points out.
We make nearly equal incomes, so we both have use for the deductions. Our mediator just brought up the deduction thing and asked what would go in the divorce decree, so he is on top of things.
(I understand in some cases the CP makes very little money, so derives very little benefit from the deductions. In those cases it could make sense to give all child deductions to the NCP in exchange for more child support.)
I found the IRS publication for divorce online here:
http://www.irs.gov/pub/irs-pdf/p504.pdf (If that link isn't good anymore, try going to irs.gov and using the search term "divorce".)
STBX will have less than 50% custody, so he can't take a child deduction unless a sign a form allowing it. So it's definitely to his benefit to try to have that put in the divorce decree, that I sign such a form.