To Ronald Reagan's lawyers and accountants, it is a secure, long-term tax haven.

To the Secret Service, it is a security nightmare nearly impossible to defend from a determined intruder. And to Reagan and his wife, Nancy, it is Shangri-La, a remote, fog-shrouded retreat where the Republican presidential candidate can mount one of his beloved Arabian horses and ride away from the cares of the world below.

"It" is Rancho del Cielo, a 688-acre "heavenly ranch," so named by reagan, that nestles on a 2,250-foot mountaintop 29.5 miles northwest of Santa barbara.

Purchased by the Reagans in 1974 at a cost of $526,000, it is the candidate's favorite hideaway. The ranch is accessible only over a twisting, one-lane road that runs 6.5 miles down the mountainside to Refugio State Beach on the Pacific Ocean below.

Reagan regards the isolation as a special blessing. He seemed so happy with it that a reporter was prompted to ask him why he wants to surrender the tranquility of such a place for the White House.

"Well, maybe because I want to see that it'll continue to be possible to have this kind of lifestyle in our country -- mainly freedom." Reagan replied. "I see it endangered more and more every day. This reminds you of how great it is."

Reagan and his fellow Santa Barbara ranch-owners enjoy the kind of economic freedom possessed by the California pioneers who took over the great Spanish land grants in the mid-19th century.

Because Reagan grazes 22 head of cattle on the ranch each summer, Rancho del Cielo is zoned as an agricultural preserve. The property tax bill last year was $862.

On the market, the ranch would bring anywhere from $1 million to $2 million, according to local sources. If it were assessed even at the conservative $1 million figure, and were not an agricultural preserve, the tax bill would be about $42,000 a year.

But there is nothing unusual about Reagan's tax status in Santa Barbara County, where the residents are both pro-agriculture and rabidly environmentalist. The state law under which Reagan's ranch is zoned protects an estimated half-million acres in Santa Barbara County alone and is credited with preventing the picturesque horse ranches in nearby Santa Ynez Valley from becoming subdivisions.

Known as the Williamson Act, the law was passed by the California legislature in the mid-1960s to help farmers to keep their land.

Reagan's ranch has been an agricultural preserve since 1971, three years before he bought it. He will have to go before the County Board of Supervisors next year to sign another 10-year contract if he wants to keep his preferred tax status. One example of what owners of land not designated an agricultural preserve pay in taxes comes from another famous Santa Barbara County couple -- Tom Hayden and Jane Fonda -- who have their own ocean-view ranch 25 miles to the east. Taxes on their 118-acre spread, which boasts a more lavish home than Reagan's, are $6,577.

Reagan's ranch is for use, not show. He saddles the horses, clears the brush and rebuilds the roof of the century-old Spanish-style home. She paints the house and helps tile the floor. They bring in firewood, oak and manzanita, for the two fireplaces that provide the only heat in the winter.

Inside the high, wooden-beamed, 1,500-square-foot, one-story home, a replica of the ranchhouse that a minor Spanish don might have used in old California, the adobe walls are decorated with Remington prints and stuffed animals. Outside is a guest book, which Nancy Reagan insists that each visitor sign.

One entry, dated June 25, 1978, reads: "A beautiful place, a nice day and the best of company." It is signedby John P. Sears, the since-deposed Reagan campaign manager.

The ranchhouse, though in an area of fire danger, is adjacent to a large pond the Reagans call "Lake Lucky." On its banks is an aluminum canoe, "The Tru Luv," which Reagan gave his wife for their 25th wedding anniversary four years ago.

"And for the 30th anniversary, I'm going to repaint it," Reagan says.

Most of the time, the Reagans keep the ranch to themselves and their close friends. The traveling press has been admitted only twice -- once in 1976 for a barbecue and once on June 24 of this year for a highly structured photo session that lasted less than two hours.

Though the ranch is far from civilization, security is a constant worry because its approaches are shrouded by stands of brush and timber. Armed Secret Service agents on horseback guard the perimeters of the ranch, but hikers have blundered onto Rancho del Cielo without being detected.

If Reagan becomes president, a helipad would be built near the ranch-house but this, too, is a worry. The fog, so thick it often saturates the ground with moisture, makes helicopter travel impossible on many days of the year.

Light planes, caught in the turbulence created when thermal updrafts meet the ocean air, also have experienced difficulty flying over the ranch.

The Santa Barbara News-Press, in extensive interviews with the candidate's neighbors, found that most of them were supportive of the Reagans but were concerned about prospective changes in the ranching environment if he becomes president. The Reagans are responsive to these concerns.

"There are some indications Mrs. Reagan doesn't want the changes that would have to be made," Santa Barbara County sheriff John Carpenter told the News-Press.

Nonetheless, Carpenter predicted that changes in security would be made, including installing detection devices around the ranch's perimeter.

The Reagans seem determined to keep the ranch as a private retreat if he is elected president. Though Rancho del Cielo is remote, it would be relatively accessible for a president who could fly into Vandenberg Air Force Base only 50 miles away.

On the recent ranch tour by photographers, Reagan made light of the hazard of winter rains, saying that sometimes Rancho del Cielo was cut off, "but not for days and days."

"When you're lucky," Nancy Reagan interrupted, "it's days and days."