Don't expect your property taxes to go down, at least not now. But the Santa Fe County Assessor's Office announced Friday that it has completed its valuation of the mansion built by Andrew and Sydney Davis on a ridgetop off of Hyde Park Road.

The land and 23,337-square-foot residence — nearly as big as the Southside Branch Library — are worth $20.4 million, according to the county. And that means an estimated $131,765 in property taxes will be flowing annually into county coffers for distribution to schools and local governments.

The house was finished more than a year ago, but it's taken that long to appraise. Back in August, County Assessor Domingo Martinez complained there had been some foot-dragging on the part of the owners in providing information about costs.

But determining the market value of the unique, 11-acre estate was complicated because, "It's probably the most expensive residential property in New Mexico," Martinez said.

There's nothing like it in the state in terms of size and quality. And to find comparable sales on which to base their valuation, appraisers had to look elsewhere in the West — to high-end communities such as Scottsdale Ariz., and Vail and Aspen, Colo.

Frank Herdman, an attorney for the Davises, said the owner's appraisal came up with a different value, but he doubted there would be any protest.

"We appreciate the fact that the county put a lot of hard work into the process and we're pleased it's over," Herdman said.

Notices of value for properties already on the tax rolls went out in April. The 2009 tax bills were mailed on Nov. 1 and are due within 30 days.

The Davises have been paying taxes on their land, which is valued at about $1.5 million, while the county has been working to appraise the improvements.

"They have paid all taxes when due and will pay all taxes when due," Herdman said.

"I think they're satisfied with what they received," Martinez said, but he added that they, like all other property owners, are entitled to protest.

While Martinez admits some other properties in the county have gone unnoticed (or untaxed), the size and location of the Davis mansion has drawn constant scrutiny. The Santa Fe Review's webcam was trained on the site off and on during the years of construction.

Davis is president of Davis Select Advisers, L.P., an investment company and portfolio manager for other real estate funds.

The county's valuation process was complex and relied on many of the most sophisticated tools and databases available to appraisers. "You can't just hold your thumb up like a painter," Martinez said. "Because it was exceptional, getting it on the tax rolls took more time than usual."

Gus Martinez, the senior appraiser who led the process, looked at homes in the Rocky Mountain West between 9,400 square feet and 15,000 square feet that sold for between $9.5 million and $36 million. Not including the land, the properties ranged between $633 per square foot and a high of $1,400, he said.

The median price of the comparable sales considered was $21.2 million, he said.

He also took into consideration something called "superadequacy." That's a measure of how overbuilt a property is for its setting. It could include things like more than one kitchen or an excess of bathrooms. But it brings down market value somewhat.

"There are only so many people in the world who can shop in that market. That reduces its marketability," explained deputy assessor Victor Baca.

Putting the Davis house on the tax rolls won't immediately lower the taxes of other Santa Feans. Down the road, it could — in theory. Adding new value means the cost of operating government and schools, and things like paying interest on bonds, can be spread out among more property owners. But taxes come down only if the agencies which receive property tax revenues don't raise their budgets. And those traditionally go up every year.

"Everything is a moving target," Domingo Martinez said.

Contact Anne Constable at 986-3022 or aconstable@sfnewmexican.com.