The District of Columbia Public Service Commission yesterday agreed to let the telephone company charge customers for local information calls after they have made six such calls a month at no charge.

The PSC ordered a one-year test of a Chesapeake & Potomac Telephone Co, directory assistance fee similar to one that has been in effect in Virginia since 1976.

D.C. telephone customers will get six free directory assistance calls each month, then will be charged 10 cents for each call dialed to the 411 information number and 20 cents for information calls to the operator.

Because the charge is expected to reduce the number of calls for directory assistance and save the telephone company money, regular monthly residential phone bills will be reduced by 34 cents, the PSC ordered.

The D.C. utility regulatory agency issued a proposed order for the one-year test that will go into effect June 22 unless the PSC reconsiders. Opponents have 10 days to enter objections to the plan.

Virginia telephone users who make more than six information calls a month have been paying a dime each for the extra calls for three years. In Virginia, 94 percent of the customers end up paying nothing for directory assistance calls because they make less than six calls a month, said Joan Rasmusson, a C&P press officer.

She said 85 percent of the calls for information are for numbers that are in the phone book.

In Maryland, a directory assistance fee has been requested and rejected several times.

About 20 states now allow the telephone company to charge for information calls.

In the D.C. plan, handicapped customers, including the blind, will be exempt from the directory assistance charge. Also exempt will be information calls from hospital patients, hotel and motel customers and coin telephones.

There will be no charge for long-distance information calls, but D.C. residents seeking phone numbers in the Maryland and Virginia suburbs will be charged for this service.Customers can get any telephone directory they want by asking for it, the C&P spokeswoman said.

When the telephone company first asked for the directory assistance fee nearly two years ago, it estimated the charge would reduce directory assistance requests by 60 percent and save $1.4 million a year.

The PSC held hearings on the proposal last November, and in its ruling yesterday said if found "substantial justification for a charge plan on a test basis."

The agency ordered C&P to make monthly reports on the number of requests for directory assistance and the number of customers who make more than six information calls a month.

The company contends that fewer than 10 percent of its customers make more than 50 percent of all directory assistance calls.

District regulators considered but did not adopt a plan to allow free information calls for numbers not in a directory.