FORT MYERS, Fla. — The Boston Red Sox have decided not to give Curt Schilling a contract extension.

That doesn’t mean that Schilling, whose contract is up after this season, definitely won’t be in a Red Sox uniform next season.

But, having been spurned in his effort to get a guaranteed contract for next year, an admittedly disappointed Schilling said he would file for free agency at the end of this season, leaving all of his options open, including a return to Boston.

The biggest factor in the Red Sox’ decision to turn down Schilling’s request was the pitcher’s age. Schilling is 40. He’s not exactly svelte, either, which also may have factored into Boston’s plan to wait until after the season to see whether they would be willing to commit millions to keep Schilling around.

Schilling, who helped pitch the Sox to their first World Series title since 1918 on only one leg in 2004, is making $13 million this year.

Schilling, who acts as his own agent, had said last year that he was going to retire after the 2007 season. But a little more than a month ago he reversed his field and said he wanted to come back in 2008, with reports that he wouldn’t be seeking a raise.

General manager Theo Epstein, who informed Schilling of the team’s decision on Wednesday at the team’s minor-league complex, said the brief discussion did not include any talk of dollars and cents.

“Age was a pretty important factor in the determination,” said Epstein yesterday. “It’s certainly not the right time to enter into a guaranteed contract for 2008. He’s going to be 41. At that age we get a little more conservative.”

The door, though, will be wide open from the Red Sox’ side if Schilling gets through the season healthy and continues to pitch effectively, stressed Epstein, who heaped a great deal of praise on the ace right-hander.

“It doesn’t mean we don’t want him back,” said Epstein. “He’s our number one, our Opening Day pitcher, and we can’t be happier about that. This doesn’t change how we feel about Curt. We have a tremendous amount of respect for him — always have, always will.”

Schilling, who thought the team had been comfortable with the dollars he talked about a few weeks ago, grudgingly accepted the decision.

“I’m human. It’s disappointing. But it’s a business decision. I get that. I have to accept that. I will file for free agency. They know that. I’ll continue working [for the 2007 season] at this point,” said Schilling.

“It was a three-minute meeting [with Theo],” said Schilling. “He asked me if I wanted the long story or the short story. I asked for the short story. It was quick. If age was one of the reasons, it doesn’t matter what I think about that. I have to accept it. I was under the impression the money [being asked for] was fine for them. This is a change of direction. It was a decision they made in the end, and like it or not, that’s the way things have to work.”

Schilling had said that his wife, Shonda, and his children had pushed him to reconsider his retirement decision, reportedly to help him earn more wins and make him more attractive to the Hall of Famer voters, though Schilling insists making the Hall is out of his hands and doesn’t motivate him.

This will be Schilling’s 17th big-league season, fourth with the Red Sox. A year ago, Schilling went 15-7 with a 3.97 earned-run average, but he was only 5-4 with a 4.58 ERA after the All-Star break. He did, though, claim his 200th victory (he’s 207-138) and his 3,000th strikeout along the way.

No one associated with the team expects his performance to suffer, nor is the situation expected to be a distraction in the clubhouse.

“It won’t be a distraction. I won’t let it,” said Schilling, who wanted to finalize the situation one way or the other before the start of the season, not wanting to do any negotiating during the year.

“I don’t pitch for contracts,” he said. “I pitch because I love the game. Now I just have to get ready for Opening Day.”

Nor will he be using the situation as a psychological boost.

“I don’t need any more motivation,” he said.

Epstein, manager Terry Francona and catcher Jason Varitek, meanwhile, expect to see the same competitive Schilling on the mound every fifth day, contract extension or no contract extension.

“I know he’s disappointed, but it won’t affect his preparation or his performance one bit,” said Epstein.

“Regardless of whether he’s signed for 10 years or one month, I’m not concerned about how he’ll go about his business,” added Francona. “He pitched with a bone sticking out of his leg (an ankle injury in the 2004 playoffs). He’ll be all right. If he wants to use that as motivation, that’s fine. Go ahead, win 20 games.”

“I know Curt’s going to be one absolute professional and prepare to have the best season he possibly can,” added Varitek.

skrasner@projo.com