The BOP release date on the website is the real number and it already has the 15% good time credit built in. What you see there assumes clean conduct throughout and no additional credits from programs like RDAP. As long as he avoids incident reports, that date stays intact all the way to the door.
Here is how the math breaks down on 78 months.
With the standard 15% good time reduction already applied, he is looking at about 66.3 months of actual time served. That is the baseline without any additional programs.
If he qualifies for RDAP and completes it, that takes a full 12 months off the sentence. That brings the inside time down to 54.3 months. RDAP eligibility requires documented substance abuse history and a qualifying conviction, so it is worth determining immediately whether he meets those criteria and getting on a waitlist as soon as possible.
On top of the sentence reduction, RDAP completion comes with an automatic six months of halfway house placement. That means instead of staying inside until the release date, he transitions to a halfway house six months early. Subtract those six months and the actual time spent behind the wall drops to about 48.3 months, just over four years on what started as a six and a half year sentence.
That is the best outcome available in the federal system short of cooperating with prosecutors. I had a 96-month sentence, kept a clean record, completed RDAP, and walked out in 66 months. The program is real and the benefits are significant. If there is any eligibility at all, pursuing RDAP from day one is the most valuable thing he can do for his timeline.
The BOP website updates the release date within 2 to 3 months of RDAP approval, so you will see the change reflected there once he is accepted into the program.