I don't believe the child support is taxable under any circumstances, just the alimony.
If his income is significantly larger than yours, it might actually be beneficial to get it done this year - he could give you more money at less cost to him because of the tax deduction.
Example: His top tax bracket is 35%. Your top bracket is 25%. Under current year tax rules, if he pays $2,000 in alimony, it costs him only [$2000 x 0.65 = 1300] $1300 out of pocket because he gets a 35% tax break on it. You receive $2000 on which you pay [2,000 x 0.25 = 500] $500 in taxes and pocket $1500. So it only costs him $1300 to pay you $1500.
Under next year's rules: If he pays you $2000 he can't deduct it so it costs him the full $2000 in after-tax dollars. He has to earn [2,000/0.65 = $3,076 ] $3,076 before taxes in order to pay you that $2,000 You don't pay taxes on it so you get the full $2,000.
In order for you to receive the same $1500 after taxes that you would under this year's rules, if you divorced next year under the the new rules he would have to earn [1500/0.65 = 2307] $2307 to pay you the same amount that would only cost him $2000 under today's rules.
Now mind you, if he's bad at math and taxes, it might possibly work to your advantage to wait until next year. I doubt the new tables on alimony will be able to accurately reflect these changes and also, if your income goes up in the future, as long as he's paying the taxes on it you will still receive the same amount instead of it being reduced by your higher tax bracket.
