Angel Martinez, Sylvan Ebanks-Blake and Dan Jones were announced on Friday.
They are now joined by Liam Graham, Curtis Morrison, Jake Beesley, Thorsten Stuckmann, Lloyd Allinson, Sadiq El Fitouri, Jay O'Shea and Charlie Raglan.
Veteran Ritchie Humphreys, 39, is in talks regarding a coaching role.
"It is never easy having to tell players that they will not be offered new contracts," said manager Gary Caldwell.
"But it is something that has to be done as we look to rebuild over the summer and shape a squad capable of competing in League Two.
"We have made contract offers to four players and hope that they will all sign.
"I would like to thank the players who are leaving the club for their service and wish them all the very best for the future."
Chesterfield will offer deals to Ian Evatt, Laurence Maguire, Dan Gardner and Rai Simons but have confirmed that 12 players will leave the club following relegation to League Two.