A power of attorney is an agreement that is recognized between the principal who is giving up his powers and the agent who will be acting on the principal's behalf. Power of attorney agreements vary widely in the powers that are conveyed and define exactly what an agent may or may not do. One such power is the right to make checks on the principal's behalf. Writing checks with a POA is simple and requires a simple phone call to the banking institution to find out their requirements.
Check the Power of Attorney agreement to ensure you have the right to write checks and process financial transactions as part of the agreement. Many times there will be clauses outlining when these powers may be used. Make sure that the reason you are writing the check meets the requirements set forth in the agreement.
Contact the banking institution that the funds will be drawn upon to find out their requirements for accepting POA checks. Each institution will have slightly different requirements. Most banks will require you to sign the name of the principal, mark that it is a POA by either writing out Power of Attorney or POA and place the agent's name on the check underneath the principal's name.
Write the check as directed by the bank institution.