My understanding is that the 10-day contracts for Tonje and Banton expire on March 1. Does that mean that they can play in the game? That their contract is until 11:59p on March 1?
In any case, by Monday, March 2, BOS will be back down to 12 on the roster. They have 14 more days that they can be under 14. By my calculation, confirmed by Spotrac, they will have spent a total of $187,257,831 on contracts, including the (2) expired 10-day contracts. That leaves them $637,169 left to spend for the rest of the season and be under the tax.
The first thing they will need to do is get the roster back to 14 by March 15 (or maybe March 14, I am not sure). I don't expect them to be in any hurry to sign anyone before the deadline for getting back to a roster of 14. They have 11 healthy plus Shugla and Harper as 2-way "call ups". And maybe Tatum at some point in this time frame. They have (7) games in that time frame (a pretty busy 2 weeks).
I have seen different numbers and predictions but I believe they can sign Shugla and Banton to "rest of season" contracts on March 15 for a cost of somewhere between $575,000 and $615,000. That would leave (worst case) about $22,000 to sign someone on the last day of the season.
A lot of people expect the last day of season contract to be Harper. I believe that he would cost $13,672 as he has 3-years of service. That would get BOS to 15 on the roster for the playoffs with about $8,100 to spare.
I think there are other variations possible. For example, if someone like Khris Middleton were to be waived before March 1 (and there are a couple of others that could be of interest if waived), BOS could sign one of those players to a 1-year "rest of season" deal instead of Shugla or Banton, and I think the cap hit would be about the same due to the way the league subsidized contracts for vets with 3+ years of experience. Someone will no doubt correct me on this as I tend to get these things at best mostly correct.
In any case, I see as the best case scenario as (which I believe can work):
March 15 Sign Middleton (assuming he gets waived)
March 15 Sign Shugla (or potentially Banton)
March ?? Tatum comes back
April 11 Sign Harper