Which is Better?

I’m an Active Duty O4 (LDO) with just over 28 years of service. The question I have is, should I elect to just go ahead and retire, or push for a MEB/PEB due to being severely injured from a medical procedure?
 
Would I forfeit any benefits that the MEB/PEB would gain me?
Since you have earned an active duty retirement you will get CRDP if your VA compensation is 50% or higher. So there is little to no financial benefit to medically retiring since you will get all of your earned pension and VA disability.

There are a few perks to medical retirement but nothing that I would consider a must to go that route. If retired via chapter 61 and you get tricare select the $300 annual enrollment fee is waived. No benefit if your family chooses the Prime option.

The only way you could net more compensation is if your DOD% was higher than your longevity which in your case is not very good since you would have to have 75% which is the max since your earned longevity is 70% AND one or more unfitting conditions would have to be designated as combat related. If those 2 things were true then your chapter 61 pension would be exempt from federal income taxes.
 
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