LTIR does not mean free capspace.

that's not how LTIR works

I'm sure Arizona would be happy to save $200,000 and gain an extra pick, but I don't see what Toronto is getting out of the arrangement...

You seem to have the best understanding of LTIR on here. Let me pose this hypothetical to you, so I better understand.

Let's say Toronto is at $75M, including Player X, who's got a cap hit of $4M, but has just sustained a career-threatening injury, and will not play next year. They want to sign Pietrangelo, but oh no! He won't take less than $8M AAV. If they acquire Brandon Dubinsky, who's in the same boat as Player X and has a cap hit of approx. $6M, what is the maximum AAV cap hit they can offer Pietrangelo?

LTIR takes up no cap space, just act like hes not on the roster

This is wrong, I'm certain. From CF's LTIR FAQ: "When a player is placed on LTIR, their cap hit remains on the teams cap payroll and it continues to count as it always did."

If you have a full roster, and one guy gets injured and can't play, he goes on injured reserve. For all intents and purposes, he's an (un)healthy scratch. We are paying him and he's on the cap.

If we bring up a replacement guy, and his salary puts us OVER the cap, then in order to make it possible for us to actually ice a full team, we can add to our maximum cap by the amount that the injured guy's cap hit is.

This only works if we are up against the cap, if we can bring up a replacement and still have $2M left in space, we can't use LTIR, because we don't need to.

TL;DR LTIR lets you spend over the cap by the specific amount of an injured player's cap hit, but at no point does it create extra space. Also, the injured guy actually has to be out LONG TERM, can't just be a day to day thing

For example, last year, the leafs had 5 million in space. We had Nathan Horton on the books, scratched forever making $5M of the $75Mish we were spending, ON THE BOOKS - total dead money. We had to give marner $10m. We trade for Clarkson who is also injured forever, and that extra $5.7M put us OVER the cap. Because we were up against the cap, we were able to put BOTH of those guys on LTIR, effectively making it so they don't exist anymore on the cap hit. Effectively reducing our cap hit to $70M instead of 75M.

Again, what's really going on his we now have a cap hit of 90M+, instead of 81.5, but it's easier to think of it as the LTIR guys being vaporized OFF the cap hit

In that example, it would be an advantage to grab another LTIR player, as Leafs would not be able to use LTIR without acquiring Dubinsky.

So $75M plus Dubinsky $6M = $81M. Leafs LTIR the $4 and $6, and it would give them $10M in space to offer to Pietro.

This is pretty well what the Leafs have been forced to do last few years by carrying Horton.

Downside of this is if they have any vets or ELCs that can/do earn bonuses, they will all be carried forward to next year and reduce their cap ceiling.

Edit: Although, in the off-season Leafs would not need to pull off the Dubinsky move, that would only be necessary if Pietro was still unsigned when the season started.

First off, I realized I screwed up, and the cap is $81.5. Let's assume it's $80, for the sake of my math problem.

I'm looking for a number in this case, just to better enhance my understanding. Is it $10M ($80M-4M-6M=70M)? Or is it $11M (70+4+6=81)? Or is it $1M, for the amount it would exceed $80M?

I realized my error, and corrected to an $80M cap.

So once you're past the post (cap upper limit), all that LTIR money vanishes from the cap. So who are teams that could take advantage of this, assuming no internal spending limits?

First off, LTIR is bad. You have to be scrunched right up against the cap to even use it, which is not good. It's always healthier and better to have natural cap space, because it accrues over the course of the season, almost like interest in a bank account.

Second, if we sign pietrangelo, and we are $5M over the cap. We bring in Dubinksy, now we are $10M over the cap - if we put him on LTIR, we are back to being $5M over the cap. Acquiring LTIR contracts is usually useless. The only reason the leafs did it is because we already had a guy who was injured forever, sitting as dead cap on our roster. By acquiring a second one, we were able to then put BOTH on LTIR and get rid of that dead space.

We had $70M on players, $5M on Horton, cap is $80M. We bring in Clarkson at $6M, now we are spending $81M, we can then put both those guys on LTIR and it's like we are at $70M. In effect though, we are operating with a $91M cap, which is bad because we're basically -$11M, meaning we can't accrue cap space and we are absolutely handcuffed in that we have to be 100% crunched against the cap in order to keep those guys on LTIR

My hypothetical imagines that both Dubinsky and Player X will be placed on LTIR.

I added to my post. This was only an in-season scenario that could benefit the Leafs by grabbing Dubinsky. In the off-season, there is no benefit. Leafs could afford Pietro without acquiring Dubinsky and just LTIR the $4M player.
$75M plus $10 = $85M - $4M = $81M.

So to put this in a real-world situation (and I'll be rounding off for the sake of simplicity):

Salary cap: $81.5M
Toronto's cap hit is currently $75M.
Alex Pietrangelo wants $9M to sign.
Justin Holl trips down his staircase and shatters both his femurs and tears his ACL. He will not play in 20-21, and has a cap hit of $2M.
Brandon Dubinsky's contract is $6M. He, too, will not be playing in 20-21.

For the Leafs to be cap-compliant by the start of the season, if they acquire Dubinsky and put both him and Holl on LTIR, what is the max they can sign Pietrangelo for?

$8.5 if they acquire Dubinksy or not.

OK, got it. Thank you! This really has been helpful for me.

No problem, now if you are quizzing me on performance bonus relief pools and stuff like within LTIR, I won't be able to help.