Westborough has added Tufts Medicare Preferred HMO to its health insurance options for Medicare-eligible retirees.

The Reliant Medical Group won’t accept Fallon Senior Insurance, “which is one of the Medicare plans the town currently offers to our Medicare-eligible retirees,” starting Jan. 1, 2014, Assistant Town Manager Kristi Williams told selectmen Tuesday night.

Reliant will work solely with the Tufts Medicare Preferred HMO, which Westborough doesn’t offer, she said.

Westborough has 71 retirees on the Fallon plan, and “55 of them use Reliant doctors,”  Williams said. The retirees have “already received letters from Reliant and from Fallon letting them know about this,” she said.

A number of the retirees have contacted town officials about the topic, Williams said.

“The message is clear that they don’t want to change their doctors,” she said.

Selectmen on Tuesday night approved offering the Tufts option to the retirees.

Selectmen Vice Chairman George Barrette said the change means that  “senior buses can run” to Reliant, at 106 East Main St., “between Lyman Street and the rotary.”

“This is something that’s necessary not only for them but also for the practicality, getting them to and from,” he said.

Williams said the town’s insurance advisory committee supported it on Feb. 28.