And options have been taken up on the deals of three of Gary Rowett's squad.
Rowett met with the players at Wast Hills yesterday to inform them of his intentions.
Jonathan Spector has been offered a two-year contract with a year's option, as has Koby Arthur.
Nick Townsend has a two-year deal, plus a year's option, in front of him.
Blues have tabled a one-year contract, with a year's option, to Charlee Adams.
The current contracts of the quartet are due to expire in June.
The year options on the contracts of Viv Solomon-Otabor, Liam Truslove and Connal Trueman have been taken up.
A fortnight ago captain Paul Robinson agreed a one-year contract.
And Blues are continuing negotiations with Darren Randolph over fresh terms.
The four loan players Blues finished the season with - Lloyd Dyer, Diego Fabbrini, Rob Kiernan and Robert Tesche - have returned to their respective parent clubs.
Rowett has expressed his hope that they could return to Blues next season on a permanent basis but admitted that nothing was at all cut and dried in such respect.