2 hours ago, BTGBullseye said:They aren't a part of the Federation at any point in any Star Trek timeline. There are individual Klingons that are either born in Federation territory, or are outcast from the Klingon Empire for dishonorable acts, who join Starfleet, but the Klingons as a race are not part of the Federation.
The closest they get is a permanent alliance made in the 27th century, and effectively all ships for both the UFP and the Klingon Empire become jointly crewed Alliance ships.
I thought an alliance was a de facto joinance (I don't know how to say it)
It's late know, I'll look it up another time