Jayson Tatum is the newest member of the NBA's $300 million club.

The Boston Celtics star has agreed to a five-year, $314 million contract extension to remain with the reigning NBA champions, a person with knowledge of the situation told The Associated Press on Monday.

The new pact will begin with the 2025-26 season and keep the five-time All-Star in Boston through the 2029-30 season, according to the person, who spoke on the condition of anonymity because the deal has not been officially announced. The Athletic and ESPN were first to report the deal.

When completed, Tatum's new supermax contract will become the largest in NBA history, supplanting the one signed last offseason by teammate Jaylen Brown, when he inked a five-year deal that will pay him up to $304 million.

Tatum averaged 26.9 points, 8.1 rebounds, 4.9 assists and shot 47 percent from the field, earning All-NBA first-team honors for the third consecutive season. Those numbers grew to 25 points, 9.7 rebounds and 6.3 assists per game during a playoff run in which he eclipsed 30 points six times, including 31 in their championship-clinching Game 5 win over the Dallas Mavericks.

He will look to add to his trophy cabinet this summer as a member of the US men's basketball team, when it attempts to capture its fifth consecutive Olympic gold. Tatum previously won gold at the 2020 Tokyo Olympics.

News of Tatum's deal came on the same day that fellow Celtics starter Derrick White reportedly agreed to a four-year, $126 million extension. All five of Boston's starters — Tatum, Brown, White, Jrue Holiday and Kristaps Porzingis — were already under contract for next season. With the new agreements inked by Tatum and White, they could all be together through 2025-26.

The deal came on the heels of the Celtics ownership group, led by Wyc Grousbeck, announcing its plans to sell all of its shares by 2028.

Barring any significant roster changes, Boston is expected to have a combined payroll and luxury tax that will exceed $400 million when Tatum's contract takes effect.

Agencies via Xinhua