The D.C. Council is considering the most extensive changes to the city's rent-control laws in two decades.

A series of bills would cap yearly rent increases, change the way vacant rent-controlled apartments are priced and make it easier for tenants to form tenant associations and to receive information on how rents are computed.

In addition, the council will consider instituting an income limit or requiring D.C. residency to reap the benefits of rent control. Those provisions would apply only to new renters.

The measures would cover the approximately 100,000 rent-controlled apartments in the city. There are 140,000 private apartments in the city, according to a city landlord association. The city's rent-control laws apply to buildings with five or more units built before 1975.

Council member Jim Graham (D-Ward 1), the principal author of the rent-control bill and chairman of the council's consumer and regulatory affairs committee, said revisions are needed to help preserve affordable housing in the city.

He cited a study by the D.C. Fiscal Policy Institute estimating that between 2000 and 2004, 15,000 units renting for $500 to $1,000 a month went off the city's rolls.

"Much of that is because of the failure of the rent-control law, which is a thumb in the dike," Graham said. "It's better than no law, but it hasn't worked as well as we would have liked it to work.''

Critics of the law say the system has resulted in rent ceilings sometimes much higher than market rent and has, in essence, removed thousands of apartments from rent control. The rent ceiling is the maximum a landlord can charge by law. Because the ceiling is often higher than the market rent, the law effectively provides no protection for some tenants.

Graham's proposal would eliminate a provision in the law that ties rent increases on newly vacant apartments to a complex formula based on tenant turnover.

Apartment building owners say the ability to charge market rents for newly vacant apartments has allowed them to renovate and improve their buildings and preserve low rents for existing tenants.

Graham's plan, among other provisions, would impose a 10 percent cap on yearly rent increases for occupied apartments. Graham said he was willing to look at the means-testing of new tenants to make sure the rent-control protections would go to those who need them most.

"We want this not to be cheap apartments for lucky people who happen to get them,'' Graham said.

The Apartment and Office Building Association of Metropolitan Washington, a trade group that represents landlords, strongly supports means-testing and residency requirements.

"If rent control is truly an affordable-housing tool, it should be for those who truly deserve it: the teacher, the police officer,'' said Nicola Whiteman, the association's vice president of government relations.

Jim McGrath, chairman of the D.C. Tenants' Advocacy Coalition, said his organization is opposed to income and residency tests. He also said the proposed changes do not go far enough.

"These are small, good things, but we need mega-good things to reform the law,'' he said. "Rent ceilings have spiraled out of control. They are casino numbers.''

McGrath said the only people benefiting from the system are those who have occupied their apartment for many years. "Everyone else is being charged market rates,'' he said.