[jellicle]

Actually, alimony is taxable to the recipient but child support is taxable to the payer.

That is, if the $4K/month is actually $3K child support and $1K alimony, the father's taxable income will be reduced by the $1K, but he's paying taxes on the rest. The ex-wife will pay taxes on the alimony received but not on the child support received.

This is one of the several reasons why women seek child support rather than alimony in divorce proceedings.