VA Patient Protection Act of 2015 This bill establishes an additional method for filing whistle blower complaints in which a Department of Veterans Affairs (VA) employee may file such complaints with his or her immediate and next-level supervisors, and ultimately with the VA after having properly filed a complaint at each supervisory level. If a supervisor makes a positive determination regarding such complaint the VA shall: (1) inform the employee of the ability to volunteer for a transfer, and (2) give preference to such transfer. The VA may not exempt any employee from such whistle blower coverage. The central whistle blower office shall be responsible for investigating all VA whistle blower complaints, regardless of whether such complaints are made by or against an employee who is not a Senior Executive Service member. The VA shall carry out specified adverse actions against a supervisor who commits a prohibited personnel action relating to a whistle blower complaint. A supervisor who commits a prohibited personnel action shall not be paid any award or bonus for a one-year period, and any award or bonus paid during that period shall be recouped. VA employees shall receive annual whistle blower complaint training. Congressional testimony by a VA employee in his or her official capacity shall be considered official duty, and the VA shall provide any such employee with travel expenses, including per diem in lieu of subsistence, during the period when the employee is so testifying.