You can choose the 50% from the Army and the other 30% from the VA but the smartest thing to do is just go with the 80% from VA because it will be Tax free. You will only receive both if it was a combat related injury.
The "option" is whether one elects to waive retired pay in order to receive VA compensation. VA comp cannot be paid to a retiree unless he/she agrees to waive retired pay dollar for dollar in the amount of VA compensation received. I can think of no situation where it would be wise to decline VA compensation. See next paragraph.
Occasionally, the VA compensation is less than the disability retired pay; this results in the following:
--Retired pay is reduced by VA offset and leaves residual retired pay (left over from the waiver).
--The disability retiree would receive VA comp + residual retired pay each month.
Regarding, "You will only receive both if it was a combat related injury." Combat Related Special Compensation (CRSC) replaces some or all of the waived retired pay for combat related disabilities. It is nontaxable. The amount of CRSC cannot exceed the dollar amount of the longevity portion of retired pay. In other words, the amount of waived retired pay in excess of the longevity portion of retired pay will not be replaced by CRSC.
50% Army and 80% VA
1. The VA compensation would not be received unless the retiree agreed to waive retired pay. Those two percentages would likely result in all the retired pay being waived and the retiree would receive only VA compensation. If the retired pay was more than the VA compensation, the disability retiree would receive VA comp + residual retired pay each month.
2. RE: "You can choose the 50% from the Army and the other 30% from the VA..." If he/she wanted to receive VA comp, he would receive the entire 80% amount, not 30%. The retired pay would be reduced as discussed in this post.
3. The CRSC for disability retirees is reduced by the amount of residual retired pay, if any.
Ron