Thousands of New Yorkers, taking advantage of rent-stabilization laws designed to keep middle-class New Yorkers in the city, are using the money they are saving on rent to buy weekend or vacation homes outside New York in places such as Florida, Connecticut, and even Switzerland.

A New York Sun investigation disclosed these examples of New Yorkers living perfectly legally in rent-stabilized apartments while owning weekend or vacation homes:

* A doctor who specializes in weight loss, Howard Shapiro, lives in a two-bedroom rent-stabilized apartment overlooking Central Park and owns a house in West Palm Beach, Fla., that was assessed at nearly $1 million, according to Florida tax records.

* William and Mada Hapworth, both doctors, have a three-bedroom rent-stabilized apartment on Central Park South with park views. They also own a Norwalk, Conn., home on Long Island Sound that is assessed at more than $1.6 million.

* Ruth Golbin, a retiree, lives in a rent-stabilized two-bedroom apartment and also owns a Key Biscayne, Fla., condominium assessed at more than $520,000. A Dade County employee in the Department of Building and Zoning, Asela Martell-Molina, said the condominium, located in the Towers of Key Biscayne, would sell for about $1 million.

* Andreas Scott-Hansen, retired from the shipping business, and his wife, Beatrice, have lived in the same rent-stabilized Fifth Avenue apartment, overlooking Central Park, for 37 years. They have owned two houses in Ridgefield, Conn., most recently a 2,600-square-foot home assessed at $825,000.

* One man who lives in a rent-stabilized apartment with views of Central Park said he flies to Switzerland once a month to stay in his $1 million, three-bedroom house outside Geneva.

Rent regulation in New York began in 1947, in part to relieve a historic housing shortage and to maintain diversity in New York City’s neighborhoods. There are now 867,697 rent-stabilized apartments and 59,324 rent controlled apartments in the five boroughs, roughly half the city’s total rental housing stock, according to the state Department of Housing and Community Renewal. Rent increases for those apartments are set annually by a government board. Living in a rent-controlled or rent-stabilized apartment and owning a second home is legal, and there is no database of people who fall into that category.

It is illegal for a tenant to occupy a rent-stabilized or -controlled apartment if it is not their primary residence. Because the city and state do not monitor these occurrences, a cottage industry of attorneys, brokers, private investigators, and buyout specialists has grown to fill the niche. Most of the evidence of rent-regulated tenants who own second homes is unearthed in the recurring effort of owners to oust tenants who live elsewhere and sublet their rent-regulated apartments or rent them out as short-term hotel rooms.

A real estate attorney for Greenberg Traurig, Steven Kirkpatrick, said, “Somebody can own a second home, a $2 [million] or $3 million dollar home, use it two or three days a week, and technically it is not their primary residence.”

John Gilbert, a top executive at Rudin Management, a real estate company with a portfolio that includes rent-regulated apartments, said there are “thousands of examples of people who live in stabilized housing and have second homes.”

“The fact that you are able to pay below-market rents, you are obviously much more able, with greater disposable income, to purchase second homes, a vacation home, a ski house, or a house at the beach,” said Mr. Gilbert, who is the former president of the Rent Stabilization Association, a landlords group that opposes rent-control laws.

Those few tenants who were willing to discuss their deals defended their practices.

Ms. Scott-Hansen acknowledged to the Sun that the below-market rent on her rent-stabilized apartment seems “like a deal,” but she added, “It’s fair. I’m not going to move out because I have another house. I’m sure you wouldn’t either.”

An editor, Kenneth Magill, and his spouse, Ludmila, who works in advertising, reside during the week in a rent stabilized two-bedroom apartment in northern Manhattan, and on the weekends drive up to their converted three bedroom house in upstate New York. The couple decided to purchase their upstate home and stay in their rent-stabilized apartment rather than buy another Manhattan apartment.

They bought the house for $115,000 in 2003, and have since spent an additional $50,000 on landscaping, an added bedroom, and a hot tub. Mr. Magill is a former employee of the Sun. Now they pay about $1,000 a month in rent for their city apartment and about $900 a month on the mortgage for their upstate home.

“For the cost of keeping the elevators running in a Midtown co-op, I have a house upstate,” Mr. Magill said. “I’m personally opposed to rent-control and -stabilization, but I didn’t make the rules, and I have to do what’s best for me and my family.”

The man who shuttles once a month between Manhattan and his house in Switzerland would speak only on condition of anonymity. He said his New York landlord has tried to oust him but has failed because no laws are being broken. “That’s the law in New York. If the law changes I will have to pay more. In the meantime, I’m going to take advantage of it,” he said, asking, “Why should I feel guilty?”

New York’s rent regulation laws are widely known as among the most sweeping in the country, and they have been a frequent lightning rod for controversy.

In 1997, the state Senate majority leader, Joseph Bruno, attempted to end the city’s rent regulations. He received death threats, encountered busloads of protesters, and had an unexplained fire in one of his district offices.

Under high-rent vacancy decontrol, established in 1994, a landlord is permitted to charge market rate for a regulated apartment if its rent rises above $2,000 and it becomes vacant. Many argue the city’s entire stock of rent-stabilized and -controlled apartments will eventually be deregulated through this provision, although it may take decades to do so.

The 1994 law also established luxury decontrol, which prompts deregulation if a stabilized apartment’s rent is more than $2,000 and its occupants’ income is $250,000 for at least two years in row. In 1997, as the result of a deal brokered by Mr. Bruno, that income threshold was lowered to $175,000.

Still, under a loophole, a tenant who consistently earns more than $175,000 a year can legally live in a rent-stabilized apartment if its rent is less than $2,000 a month.

The associate director of New York State Tenants and Neighbors, a tenant advocacy group, Michael McKee, said that it was “very rare” for a wealthy family to occupy a rent-regulated apartment. “The income of a tenant is and should be irrelevant,” Mr. McKee said. “Many people start out in a rent-regulated apartment when they are making less money, and they make more over time. Some people think they should be forced to move. I disagree with that,” he said.

“The rent regulation system is constantly under attack. If you want to talk about people who have money, talk about landlords – these are some of the richest people on the planet, and they are certainly not losing money on rent stabilized apartments,” Mr. McKee said.

Mr. Bruno told the Sun that further reform of rent stabilization and rent control is unlikely until 2011, when the current law expires. “When we did the luxury decontrol, there were others who were bucking, kicking, and screaming all the way,” Mr. Bruno said.

Nevertheless, he said that his legislative effort led to the deregulation of at least 20,000 apartments that were occupied by wealthy residents.

A spokesman for the state Department of Housing and Community Renewal said 1,900 certified apartments have been deregulated since 1997 because of luxury decontrol.

Mr. McKee, the tenant advocate, said that many of those units were deregulated incorrectly, because tenants failed to submit paperwork, or to the detriment of poor tenants that needed the below-market rents.

Landlords who are watching the real estate market and who now must bear higher fuel and insurance costs say they are tired of subsidizing their tenants’ vacation homes.

A veteran New York building owner and attorney, Maria Sachs, said that some owners of buildings with rent-stabilized apartments “bear this burden of supporting someone who is better off than they are.”

“It is an irrational system of distribution on the benefit side, in terms of who gets the apartments, and on the other side – the imposition of the costs on the landlord,” Ms. Sachs said. “The person who can afford the second house isn’t really in need.”

An agent who is paid by landlords to broker buyouts with tenants in rent-regulated apartments, Michael Grabow, said he receives frequent complaints from owners about tenants with second homes. “I tell them, you may not like this law, but it’s the law,” Mr. Grabow said. “Tenants who pay $450 a month are accumulating a lot of money. They want a place in the Adirondacks, and there is not a thing you can do about it. They get angry, but I tell them, ‘It’s not the tenants’ fault. Be angry at the system.'”

In October, Mayor Bloomberg outlined his administration’s expanded second-term housing plan to build or preserve 165,000 units for low-and moderate-income New Yorkers by 2013. The cost of the 10-year plan, from 2003 to 2013, is about $7.5 billion. Both candidates in the recent mayoral election spoke of the need for more “affordable housing” in the city and vowed to create new units to be set aside at below-market prices.

Mr. Gilbert, of Rudin Management, said that the private sector would bear more of the cost of building new housing if rent regulation is abolished or phased out at a quicker pace.

“If there is an upside for investors and developers, they will build. If you cap their profits with rent stabilization, they won’t build,” he said. “There will always be a need for the government to meet the needs of the housing segment that the private sector can’t meet. But you would have less of a need if you had more of a free market.”