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Gillingham have until Saturday to confirm their retained list.
Head coach Ady Pennock and director of football Peter Taylor have been busy this week assessing their options and contacting players.
Gills’ management team was only put in place on Monday and so they are playing catch-up.
The Gills need to inform the football authorities of those players on expiring deals they wish to retain. Those aged under 24 would otherwise be able to leave for nothing.
Many of the 12 who are out of contract are senior players and they are effectively already free agents.
One of those players that the Gills are likely to want to keep is goalscoring striker Cody McDonald, but he may well be in demand, and the club have no hold on him.
Taylor said: “The retained list will definitely be out by Saturday, 100%, we have to do it, but it is more for our younger players that we have to do it.
“If we have a couple of players under 24 years old and they are not on the retained list then they can go for nothing.”
The Gills are keen to speak to all of their players individually before making an announcement, although youngsters Emmanuel Osadebe and Mitchell Dickenson have already confirmed their exit on twitter.
Defender Zesh Rehman has tweeted that he has “a number of offers” that he is considering.
Teenage keeper Henry Newcombe also posted a message on twitter, saying he had been released.
He said: "Just want to say a massive thankyou to all the staff I have worked with, right the way from the academy and the managers I have worked with in and around the first team, for their hard work and guidance over the last 11 years."
It is understood that youngsters Elliott List and Greg Cundle are likely to be offered new terms.
Taylor and Pennock are also holding talks with potential new recruits and it's likely to be a busy summer on the transfer front.
Chairman Paul Scally said: “I think it is fair to assume that there will be a lot of changes on the playing side.”