Last week proponents said that rent-regulated buildings would be exempt from the tax.

But value is calculated on the basis of rental values in comparable, often rent-regulated, buildings.

Sigfeld Realty was the landlord before it began converting the completely rent-regulated, 194-unit building in 1987.

But not all poor tenants in rent-regulated buildings would be harmed by the end of regulation.

Mr. Spinola said the increases could particularly hurt owners of rent-regulated buildings.

Unlike last year, she said, this year the city was able to separate out rent-regulated buildings and base its estimates on market-value rentals alone.

My impression is that it is illegal to reduce the housing stock of rent-regulated buildings unless the owner is doing so for his own use.

He gave the example of $150,000 used to replace the windows in a 50-year-old, 100-apartment rent-regulated building in the Inwood section of Manhattan.

Nor does the installation in a rent-regulated building make the owner eligible for a rent increase under the major capital improvement program.

When owners of rent-regulated buildings make major capital improvements they are allowed to increase rents by 1/84 of the cost of the improvements.