I would once again recommend The Athletic where our sometimes listmember Derek Bodner has several stories about this.
Projected space (based on current contracts only) $59,153,364
(Note: relevant cap holds, if you want to do some free agency math on your own: Jimmy Butler will count $30.669 million against the cap until he’s either renounced or signed to a new contract, either in Philadelphia or elsewhere. Tobias Harris has a $22.2 million cap hold and JJ Redick $15.9 million).
...that amount of room provides the Sixers with a bit of insurance should either Butler or Harris sign elsewhere, or if the Sixers decide they don’t want either back. Slot in Harris’ $22.2 million cap hold and the Sixers could have upwards of $37 million in space available if they renounce Butler and JJ Redick. That may not be the plan, especially since Redick would be a costly loss, but it is a contingency option if they feel they can get a long-term contributor instead. Should it happen the other way – Harris signs elsewhere and Butler sticks around long-term – and the Sixers could be within the ballpark to offer a 30 percent max with a few more moves.