GUILDERLAND — The elected boards representing the town and school district each independently voted on Tuesday night to join forces in fighting an assessment challenge from 20 Mall. The mall claims it is worth about $8 million while the town has it assessed at nearly $12 million.

The boards are hiring the law firm Girvin & Ferlazzo, splitting the costs, with the school district paying 70 percent and the town, 30 percent since the school collects far more in tax money than the town. This is similar to an arrangement the town and school district had when battling a challenge earlier from Crossgates Mall.

The school board’s vote was unanimous, but the town board had one dissenter, Councilman Warren Redlich who proposed that the town board put its assessment cases together and put them out to bid for a better value, defending them vigorously.

Guilderland’s assessor, John Macejka, said yesterday that the 20 Mall, located on Route 20 near the intersection with route 155, is currently valued at $11,747,000. The mall was assessed at that amount when the town went through revaluation in 2005, he said, and the assessment had not been challenged earlier.

“It seems to me they were quite comfortable with that value,” said Macejka. “There’s no indication here even of an informal hearing,” he said, looking through records kept by his predecessor, Carol Wysomski.

On July 22, the mall, owned by William Lia and represented by Paul J. Goldman of Segel, Goldman, Mazzotta & Siegel, filed a notice of application for review of assessment with the New York State Supreme Court, Macejka said; it is the lowest court in the state’s three-tiered system.

“They believe their value is $8,008,000,” said Macejka. “We will vigorously defend the assessment.”

While he declined to give specifics on how the mall had been assessed because the assessment is under litigation, Macejka did say, “It seems like a very active and busy mall and it looks like during tough financial times, it’s generating income.”

Goldman sees it differently. Guilderland’s assessments, he points out, are no longer at true value. The town has a state-set equalization rate of 79 percent. With the current assessment of $11,747,000, that translates into a value of $14,852,000 for 20 Mall, Goldman said.

“The property is over-assessed,” he said, stating a fair full value would be $10 million; with the 79-percent equalization rate, that would bring it to just under $8 million.

Goldman also said that 20 Mall was inequitably assessed. “You have to equalize by the full-value number,” he said.

Because the mall was built 35 or 40 years ago, and includes enclosed shops, Goldman said, it is not as desirable to merchants. “They’re assessing it at 100 bucks a foot, and it’s tough space in back,” said Goldman, who lives in Guilderland. Modern malls, he said, have shops that are shallower. “The deeper space is less valuable,” he said, “and the enclosed mall is antiquated and tough to lease.”

The school district, Macejka said, “stands to lose over $3 million in assessed value…The money, if it had to be refunded, is substantial.”

Guilderland schools Superintendent John McGuire said that the school board, which met in executive session over the certiorari issue, had not discussed setting money aside in escrow in case the town’s assessment did not prevail.

Tax roles were finalized on July 1, and challenges to assessments had to be filed by Aug. 1. Guilderland had seven commercial challenges this year. “I don’t have to juggle between 20, 30, 40 certioraris,” said Macejka. “It’s manageable.”