((a)) Except as provided by subsection (c), a Reserve of the Army, Navy, Air Force, Marine Corps, or Coast Guard who because of the Reserve’s earlier military service is entitled to retired or retainer pay, and who performs duty for which the Reserve is entitled to compensation, may elect to receive for that duty either—

((1)) the pay and allowances authorized by law for the duty that the Reserve is performing; or

((2)) if the Reserve specifically waives those payments, the retired or retainer pay to which the Reserve is entitled because of the Reserve’s earlier military service.

((b)) Except as provided by subsection (c), a Reserve of the Army, Navy, Air Force, Marine Corps, or Coast Guard who because of the Reserve’s earlier military service is entitled to a pension or disability compensation, and who performs duty for which the Reserve is entitled to compensation, may elect to receive for that duty either—

((1)) the pension or disability compensation to which the Reserve is entitled because of the Reserve’s earlier military service; or

((2)) if the Reserve specifically waives those payments, the pay and allowances authorized by law for the duty that the Reserve is performing.

((c)) Unless the payments because of a Reserve’s earlier military service are greater than the compensation prescribed by subsection (a)(1) or (b)(2), as applicable,, a Reserve of the Army, Navy, Air Force, Marine Corps, or Coast Guard who because of the Reserve’s earlier military service is entitled to a pension, retired or retainer pay, or disability compensation, and who upon being ordered to active duty for a period of more than 30 days in time of war or national emergency is found physically qualified to perform that duty, ceases to be entitled to the payments because of the Reserve’s earlier military service until the period of active duty ends. While on that active duty, the Reserve is entitled to the compensation prescribed by subsection (a)(1) or (b)(2), as applicable,. Other rights and benefits of the Reserve or the Reserve’s dependents are unaffected by this subsection.

((d)) The Secretary of Defense shall prescribe regulations under which a Reserve of the Army, Navy, Air Force, Marine Corps, or Coast Guard may waive the pay and allowances authorized by law for the duty the Reserve is performing under subsection (a)(2) or (b)(2).