His agent, Willie McKay, who infamously instigated his transfer request during last January's transfer window, has confirmed there is a clause in Barton's contract saying he can talk to another club if they offer £5.5m.
"This is Joey Barton's clause, not Manchester City's and it is a clause they were happy to put in," he told BBC Sport.
"If a club offers £5.5m, it is Joey's right to speak to that club if he wants to, or not if he doesn't want to."
City were obviously happy with the clause (unless they didn't spot it!!) and I'm amazed they agreed to it.
Barton has presented City with many problems and I'm sure that at some stage they wished they were rid of them. But even if that was the case, I just cannot see why they would ever regard £5.5m as a far amount for a player of Barton's undoubted ability.
He may have been a nuisance but he has always shown the potential to become an England international, which he may soon achieve.
With that being the case, I'm sure Everton will come back with a sufficient offer. Barton grew up an Everton fan and despite being released by them as a schoolboy, I worry the lure of joining his boyhood idols will be too strong to resist.
If so, City will only have themselves to blame. Unless, of course, the clause was snuck in by the meddling McKay.