What it is
Which retirement system you are under: Blended Retirement System (BRS) for everyone joining since 2018 and those who opted in, or the legacy High-3 system for longer-serving members who stayed.
What goes wrong
If this says the wrong plan, your TSP matching is wrong too. BRS members get the automatic 1 percent and matching; High-3 members get neither. This field and your TSP block must tell the same story.