CHET RILEY'S pre-1780s barn in Hampton is one of more than 400 structures in 83 towns enrolled in the state's barn tax incentive program.

“If people know their taxes won't go up just because they've repaired their barn, it provides a real incentive for them to save these buildings,” Riley said.

In 2002, the Legislature passed a law, RSA 79-D, known as the barn tax incentive, which also covers silos and other agricultural buildings, according to the New Hampshire Preservation Alliance.

The law allows cities and towns to grant property tax relief of 25 to 75 percent of the assessed value of the building and the land beneath it to barn owners who can demonstrate the public benefit of preserving their old farm buildings.

“People had these old barns and they wanted to fix them up, but it costs a lot of money to preserve them,” Riley said. “What would happen is once they repaired the barn, the assessor would come along and jack up the assessment. It was a real disincentive for people to improve their barns.”

The 10-year renewable easement requires barn owners to maintain their buildings.

“It's a cultural heritage that's important to the state,” Riley said. “We lose a lot of barns every year. We need to save these cultural artifacts.”

In Haverhill, Susan Brown has used the incentive program to restore her late-1700s barn, a costly and time-consuming endeavor that meant repairing or replacing everything, from the foundation up.

“You can't just let a barn sit there and rot. That's just not good stewardship, so we took care of it,” she said. “But when this incentive came up and they said it would cut our taxes, we said, ‘Oh, yes!'”

Brown said the money she saves on her taxes will never come close to what she's put into the barn, but it has provided a bit of relief.

Carl Schmidt, chairman of the New Hampshire Historic Agricultural Structures Advisory Committee, said that while the list of properties being saved under the incentive program continues to grow, “this important tool is still under-utilized and I hope that more barn owners and municipalities embrace this opportunity.”

A lot of towns and residents in New Hampshire may not know about the program, said Jennifer Goodman, executive director of the New Hampshire Preservation Alliance. With the 10-year anniversary of the law's passage near, there's a push to get the word out.

“The Preservation Alliance wants people to consider what's important to save or revive in their communities,” said Goodman. “We also want the hundreds of other barn owners out there that haven't yet participated in this barn incentive program to know that there is this option for them.”

A total of 83 towns participate; Nashua and Grafton signed on last year.

Peterborough continues to lead the state in the number of structures — 23. Kensington is second with 17 and Cornish has 16.

The most notable increase took place in Plainfield, with 10 additional structures put under easement, bumping the total to 18. Deerfield added four more structures for a total of eight, and the city of Concord increased from 10 to 13 structures. The deadline for 2012 applications is April 15. For more details about the program, visit www.nhpreservation.org.

On March 24 and 25, the alliance hosts its Old House and Barn Expo at the Center of New Hampshire, Radisson Hotel in Manchester.