Promotion Board Opt-Out Opportunity Act of 2017 This bill authorizes the Department of Defense (DOD) to permit an active duty officer or a reserve active-status list officer to request exclusion from consideration by a selection board for promotion to the next higher grade. A military department may approve such a request only if: (1) the basis for the request is to allow an officer to complete a broadening assignment, advanced education, another assignment of significant value to DOD, or a career progression requirement delayed by the assignment or education; (2) the military department concerned determines that such exclusion is in its best interest; and (3) the officer has not previously failed to be selected for promotion to the grade for which such exclusion is requested.