William Chisholm Projected to Spend $500M on Salaries and Tax Penalties in His First Season as Celtics’ New Owner

One of the most famed franchises in American sports is changing hands. The Boston Celtics have been sold to William Chisholm at an evaluation of $6.1 billion. Though his stake has not yet been disclosed, he’s believed to be the new majority owner. Chisholm will need to keep his checkbook ready because the reigning champions are projected to have the largest payroll in NBA history next year.

Boston boasts a well-rounded squad, but that plethora of talent comes at a price. Jaylen Brown’s massive $304 million extension kicked in this season, while Jayson Tatum’s similarly luxurious $314 million extension begins in the fall.

Eleven current players are under contract for 2025-26. As things stand now, Boston’s payroll is projected to be $225.5 million for next season. A hefty luxury tax will be tacked onto that of around $219.3 million.

Fortunately, with the majority of the team returning next year, the Celtics won’t have to make too many moves. But by the time their roster is completely filled out, Boston could have a tab north of $500 million.

The timing of the ownership sale coincides with Boston’s projected to have the largest payroll next year in NBA history.

The Celtics have $445M in projected salary/tax penalties in 2025-26.

That number could balloon to over $500M once the roster is filled out.

— Bobby Marks (@BobbyMarks42) March 20, 2025

The Celtics will have at least four spots to fill in the offseason, but with such a high payroll already, it will be hard to add any notable talent. Al Horford is the only key free agent for the Celtics this year, and even though the former All-Star’s performance is declining, it won’t be cheap to bring him back.

With the NBA introducing a stricter luxury tax policy to penalize high-spending teams, the Celtics will have to get creative if they hope to keep the band together. Even if Horford were to accept a veteran minimum contract around the area of $3M, it would cost Boston an additional $25M in tax.

Boston has one of the most complete starting lineups in NBA history. Payton Pritchard has stepped up as an excellent bench piece too, but outside of him, the Celtics don’t possess elite depth behind their stars. This could become even more of an issue next season if the team is unable to retain Horford.

The league will introduce starting on July 1 more stringent luxury tax rules that penalize high spending teams.

For example

Every $3M that Boston spends on a Free Agent could cost an additional $25M.

Their key free agent is veteran Al Horford. https://t.co/MnnCS43s6W

— Bobby Marks (@BobbyMarks42) March 20, 2025

Chisholm likely knew what he was getting into when he forked over $6 billion to take over the historic franchise. But for the billionaire’s sake, hopefully he realized how the league’s new luxury tax rules would affect the most expensive roster in the NBA.