It emerged last week that talks had begun between the two Barclays Premier League sides over the sale of the England international, who is out of contract at the end of the season and has for some time been linked with a move away from the Reebok Stadium.
And it seems a deal is now imminent, with Coyle revealing on Friday that agreement over a fee - believed to be in the region of £7million - for the 26-year-old has been reached.
"There has been a fee agreed between the clubs and we have now given Gary's representatives permission to speak to Chelsea," said Coyle.
"That is where we are with it. We obviously have a game [on Saturday] and I have said to Gary that he has to be focused on giving everything for Bolton Wanderers, because he knows Bolton Wanderers has been terrific for him just as much as Gary has been for us.
"That is why they have representatives - to sort that out - and whatever January 1 brings, it will bring."
Andre Villas-Boas, the Chelsea boss, insisted on Friday afternoon that a deal had not been completed and described the club and player as "miles apart" over personal terms.