Bowe Bergdahl was Pfc. Bergdahl when he walked off his post in Paktika Province, Afghanistan, and was captured by the Taliban. Five years later, however, when the White House exchanged five Taliban detainees for his release, he was Sgt. Bergdahl.
According to the Department of Defense, prisoners of war and those under missing status continue to be considered for promotion along with their contemporaries. They must be considered for promotion to the next highest grade when they become eligible.
For enlisted, it is based on time in grade and time in service. The eligibility for officers is based on the date of rank in their current grade.
A notable story is of then-Cmdr. James Stockdale. When he was captured and sent to the Hanoi Hilton, he was the most senior POW and so was the ranking officer among the prisoners there. When Lt. Col. 'Robbie' Risner was also captured, he outranked Stockdale by time in grade.
Later, a newly captured naval pilot informed Stockdale of his promotion to captain, he assumed command again.
This continues for prisoners of war but stops for those on missing status when they are presumed dead under Title 37 of the U.S. Code, section 555.
This happened with 1st Lt. John Leslie Ryder. His aircraft, nicknamed "Bird Dog," went missing during a visual reconnaissance flight during the Vietnam War on June 9, 1970.
During the flight, the crew failed to report in by radio and calls were not answered. The search could not be mounted until the next day. The search continued until the 19th to no avail. A year to the day later, Lt. Ryder was promoted to captain.
Payment is also changed from regular enlistments. Instead of being involved in DFAS, the payment is authorized by Congress and made directly through the Secretary of the Treasury, tax-free. Any earnings, leave and money, are still given to the individual at their appropriate rank and are held until return.
There is also no limit on leave accrual, meaning it is well deserved for the returning service member to take all of the leave at two and-a-half days per month.