The experienced frontman was one of several players targeted by the Bantams when the club announced the wage bill was going to be slashed after failing to secure promotion from League Two last season.
Graeme Lee and Paul McLaren both moved on but Boulding has offered to take a drop in his income in order to stay, much to the delight of McCall.
"Micky took a sizeable cut, which he didn't need to do. It's a terrific gesture and just shows how much he wants to be here," McCall told the Telegraph and Argus.
"He knew the situation with the club needing to get some of the big earners off the wage bill and was happy to come in and sort something out."