Paying your health care agent (or "attorney-in-fact" in some states) could spell trouble from a legal standpoint. Many laws governing health care directives state that the agent cannot have a monetary interest in the patient's care, so courts would likely look askance on the validity of the health care document if it involves a payoff. (This is different from a financial power of attorney, under which an agent may legally be compensated.)

You cannot leave a conditional gift in your will, either, such as: $1,000 to John Jones if he serves as my health care agent. And remember that the will kicks in only after a death -- and health care agents may serve during a serious illness or injury, after which you recover and live in fine fettle.

Your only options are to leave a bequest of money in a will and know that it will be distributed if and only when you die. Or you could set aside the money and explain in a letter attached to the health care document that you want the health care agent to get the money if he or she should have to act on your behalf.