Salary cap questions for dummies

[dannyboy35]

   I’ve loved the Celtics for years but I’m the “other side of the brain” when it comes to math. I honestly really struggle with it that it’s overwhelming dealing with financials. 
  So I read a lot here in this blog and people seem really knowledgeable about cap stuff. But to be honest. I read the explanations snd still have trouble. Ha.
   I’m not sure I could even read literature on the salary cap and understand it  . So basically, if you could humor a big fan like me, can the Celtics theoretically have all of the following players AT ONCE  in the future?
Tatum maxed
Brown
Smart at 25 per year
Theis at 12 a year
A max player salary open slot for a free agent when Kemba deal is up in the year starting 2023-24? Or do we need to not have some of the other assets? Or some adjustments with those numbers to make it possible.
  If these are correct ,can you let me know? I’m trying to basically dream up what’s possible but the numbers are just so confusing to me. Thanks in advance!

[liam]

   I’ve loved the Celtics for years but I’m the “other side of the brain” when it comes to math. I honestly really struggle with it that it’s overwhelming dealing with financials. 
  So I read a lot here in this blog and people seem really knowledgeable about cap stuff. But to be honest. I read the explanations snd still have trouble. Ha.
   I’m not sure I could even read literature on the salary cap and understand it  . So basically, if you could humor a big fan like me, can the Celtics theoretically have all of the following players AT ONCE  in the future?
Tatum maxed
Brown
Smart at 25 per year
Theis at 12 a year
A max player salary open slot for a free agent when Kemba deal is up in the year starting 2023-24? Or do we need to not have some of the other assets? Or some adjustments with those numbers to make it possible.
  If these are correct ,can you let me know? I’m trying to basically dream up what’s possible but the numbers are just so confusing to me. Thanks in advance!

In a short I don't know that much but they could do it if they'd pay the tax. Lots of tax.

[PhoSita]

I'd recommend following @dangercart on Twitter, and checking out his blog.  He consistently provides deep, well-reasoned analysis on where the Celts stand in relation to the cap and how that limits what they can do.

[Celtics2021]

It’s impossible to have room for a max free agent at those numbers. You’d need the cap to jump about 40% over the next two seasons, and that’s not possible, as the players an owners limited annual growth of the cap to no more than 10% this fall as part of their deal to not have a massive cap contraction.

EDITED because I was incorrect about expansion fees and BRI.

[nickagneta]

It's possible to have all those players on the team at those salaries, along with Kemba at his salary. But the team would never get under the salary cap to create the space that would be necessary to sign someone at a salary level close to Kemba's salary by salary dumping Kemba.

But.....the Celtics could have all those guys signed and then deal Kemba for a player that would have a salary that would be close to Kemba's. Like for instance the C's could have Smart, Tatum, Theis and Brown signed as you say and then at the deadline in Kemba's last year he could be dealt as an expiring contract to a team wanting to shed salary that following off-season.

Like maybe by that point Toronto is in rebuild mode and would move Siakam or Portland would be and might want to move on from Damian Lillard's giant contract. Things like that could be possible.