Everyone is summing things up pretty well, and I agree in general:
1. BOS will stay under the tax this season to reset
2. BOS will pay tax next season, maybe even go over the 1st apron
Of the 12 contracts, 9 are locked in, 2 are team options (Hugo at $3.0M and Baylor at $5.0) plus Paul George is a player option at $56.6M. I would say 99% sure that BOS picks up Hugo and 99.99999% sure George picks up his player option, but Baylor at $5.0M may not be picked up, there could be vet mins available that offer more value.
Every owner that I have heard (or seen reported) is saying the same thing, we will spend but we will not go over the 2nd apron. They are all quoting the same message (yes, I am implying that this is not by accident). They have all accepted the 2nd apron as a hard cap. For BOS, that was true for the previous owners and is true for the new owners.
So that results in a $20M range if you are over the tax and under the 2nd apron. The range for BOS is even smaller since they are already projecting to be over the tax next season. For BOS, their "discretionary" spending will only be in the $5M to $10M range for 2027-28, as things stand. They can increase this by trading Hauser or not picking up Baylor. I don't think White is going anywhere. I guess Queta or "Clank" Robinson could be traded off, but I don't see either as likely.