"How much federal and state taxes can be with held from the pension check if he owes 66,000 in back child support?"
Since there is no special tax benefit for income used to pay off child support, his estate will owe the full tax amount on any pension distribution. The withholding might be more or less than is owed; if the withholding is less than is owed, the estate will owe a big bill when it files a final tax return, even if that means taking money back from the heirs. Money should not be distributed until the tax situation is fully understood and dealt with. See an expert.
