The answer is yes, however if you make the payment then the court would unlikely enter an order that you are in contempt. If I were your attorney I would take care of everything prior to Court...Judges do not appreciate the funds being available all of a sudden the day of a contempt motion.
Attorney McCabe is correct. If the court order says you need to pay child support, then that is what you need to pay. You can try writing "Advance Child Support Payment" in the memo section of the tax bill and pay it before court. The judge may then accept that the payment (or part of it) is sufficient as child support, but the problem you also have is if the bill is in both of your names and you both are liable for it. If you both are liable for the tax due, it is unlikely the judge will treat the payment as payment in lieu of child support because the tax bill is also your obligation to pay.
Brian S. Karpe, Esq. (860) 242-2221 Note: This response DOES NOT constitute legal advice and therefore no specific action should be taken in reliance thereon. No attorney-client relationship is created through this response. You should speak to an licensed attorney in your state who is competent to answer your question before taking any action with regard to this question.