Work it out
Which one applies to me
Two questions that are decided by rules rather than by preference, so they can be walked rather than argued. Each answer shows the path that produced it, says what would change it, and names who actually decides.
Which retirement system am I under?
Am I under legacy High-3 or the Blended Retirement System?
When did you first enter military service in any capacity?
The rule turns on DIEMS — date of initial entry to military service — which is not your PEBD and not necessarily the date you started your current commitment. It includes an academy appointment, ROTC contract, or prior enlisted service.
5 possible answers. Nothing here is saved anywhere but your own browser.
Which TRICARE plan applies to me?
What healthcare am I actually eligible for right now?
What is your status today?
Eligibility is decided by status before it is decided by preference. Most of the confusion about TRICARE is people comparing plans they cannot enrol in.
8 possible answers. Nothing here is saved anywhere but your own browser.
Why these two and not more
A decision tree is only honest where a rule decides the outcome. "Which retirement system am I under" turns on a single date, and "which TRICARE plan am I eligible for" turns on status — both are facts, and a wrong answer is a wrong fact rather than a difference of opinion.
Questions like whether to take the lump sum, or whether to elect the survivor plan, look like they belong here and do not. They depend on what you value and on things nobody knows — how long you will live, what returns will be, who will depend on you in thirty years. Walking someone through four questions to a confident answer on those would be dressing a judgement up as a computation, so they are argued in the articles instead, with the trade-offs left visible.