The NBA's new collective bargaining agreement, released late last month ahead of free agency, came with a previously undisclosed side letter indicating Ben Simmons has received credit for a year of service for the season in which he held out from the Philadelphia 76ers and was eventually traded to the Brooklyn Nets, sources familiar with the matter told ESPN on Wednesday.

Years of service come into play when determining whether players are eligible for maximum contracts of certain sizes and for other benefits. Counting the 2021-22 season at issue, Simmons now has seven official years of service in the NBA. Officials from several teams had argued Simmons should not receive credit for the 2021-22 season, sources said.

The side letter is intended as a standalone, applying only to Simmons, and is not intended to set precedent for future cases, sources told ESPN.

Simmons had requested a trade from the Sixers during the 2021 offseason, following Philadelphia's Game 7 loss to the Atlanta Hawks in the second round of the playoffs.

Simmons showed up to training camp before the 2021-22 season, but then refused to fully participate or play in regular-season games, citing his mental health. In February 2022, the Sixers traded Simmons to the Nets in the deal that sent James Harden to Philadelphia.

Simmons continued to sit out in Brooklyn, citing knee and back issues before undergoing back surgery in April 2022 to repair a disk.

The Nets paid Simmons his salary in full for the portion of the 2021-22 season he spent in Brooklyn, but the Sixers had previously withheld about $20 million of Simmons's salary, arguing he had breached his contract by refusing to play. Simmons and the National Basketball Players Association filed a grievance against the Sixers in April 2022 to recoup some of that salary.

The two sides settled the grievance in August 2022, allowing Simmons to recoup a portion of that salary, ESPN's Adrian Wojnarowski reported. Terms of the settlement have not been disclosed.

Harden has now requested a trade from the Sixers, and in the event Harden is not traded and then refuses to report to camp, different rules would apply to him because he is in the final year of his contract, league sources told ESPN.

A separate clause in the CBA -- which existed in prior versions of the agreement -- holds that any player who "withholds playing services for more than 30 days after the start of the last season covered by his contract" could be deemed to have violated his contract and prohibited from entering free agency or signing with "any other professional basketball team unless and until the team with which the player last played expressly agrees otherwise."

The rule allows incumbent teams to block any player deemed in violation from entering free agency and signing elsewhere -- including with professional teams outside the NBA, league sources confirmed to ESPN.