Steve Hart’s three-family Boerum Hill brownstone is worth $2.2 million, according to a property assessment letter he received this month.

“I’m going to file a complaint or an adjustment form with the city because it’s a completely outrageous sum of money,” the artist and actor, who manages two properties with his wife, said. “This house could never sell for anywhere near that.”

Such letters are causing consternation throughout the city. “People are just tearing their hair out. Everybody’s upset,” the president of the nonprofit Small Property Owners of New York, Roberta Bernstein, told The New York Sun.

Ms. Bernstein said she has already received 20 phone calls from distressed members of her organization. Some of them, she said, haven’t even opened their letters. Ms. Bernstein, who owns a building on the Upper East Side, hasn’t opened hers, either. “I put it in my drawer of things to review,” she said. “I don’t want to have a heart attack.”

The January Notice of Property Value letters have been sent, and the message received: Property taxes are going up. Despite caps on annual tax increases for small building owners, the city’s finance department estimates that property values have risen 19% since last year, putting the total market value of New York’s real estate at $802.4 billion.

“If people own townhouses and brownstones and saw market values of $1 million for 20 years, and now they’re looking at values of $7 million or $11 million. It’s scary,” a tax attorney Joel Marcus, said. “Whenever they do the quick math and find out the tax rate, it’s horrible. They’re not being taxed at market value because of the limitations, but it causes a scare in the city.”

“We’ve been hearing about it for about four or five years now,” the director of government affairs for the Rent Stabilization Association, Frank Ricci, said. Even if the present tax system is modified, he added, it will still squeeze property owners too hard. “It’s a system that’s really, really broken, and it needs some repair,” he said.

Last year, 39,700 of the city’s roughly 1 million homeowners appealed their property tax assessments, the director of operations for the city’s tax commission, Myrna Hall, said. The city gave out $2 billion in reductions, she said.

Mr. Hart said he has already requested his appeal forms.

“For all the things you read about programs creating affordable housing, they’re killing twice as much affordable housing as they’re creating, with the tax rates,” Mr. Ricci said. “If the city thinks they’re going to build their way out of the affordable housing crunch, they’re wrong.”