Created in 1963, the tax was devised to generate revenue when the city was approaching its constitutional limit on property taxes. The law affects business owners in Manhattan below 96th Street (though areas around the World Trade Center were exempted after Sept. 11), who must give the city 3.9 percent of what they pay in rent, with the bill rising as leases are renegotiated and fees to landlords go up. Often a tenant is paying this tax in addition to a real-estate tax already levied if, say, the tenant is occupying ground-floor space in a co-op building.

On a recent visit to San Francisco Clothing, which has sold crisp shirts, cardigans, dresses and other garments suitable to its Upper East Side location since the late 1960s, I went through the math with the owner Howard Partman. When he moved to the store’s current location on Lexington Avenue in 1973, his rent was about $1,500 a month; he now pays close to 20 times that much, with rising taxes on top of it. Although his is largely a story of success, he is dealing as well, he said, with diminished foot traffic in part because the ever-rising fortunes of the neighborhood take greater numbers of people away on the weekends and in part because the shopkeepers who have not been able to stay afloat produce the empty retail spaces that leave fewer incentives for turning off your computer, leaving the house and going out with the ambition to buy something. In Mr. Partman’s case, the commercial rent tax seems especially unfair, given that he works to sustain local garment manufacturing by making what he designs in New York, rather than getting it fabricated cheaply abroad.