A new $400,000 system allowing District of Columbia official to keep closer tabs on revenue collections has left hundreds of city taxpayers waiting for up to an hour to pay property taxes and grumbling about government inefficiency.

The city's Department of Finance and Revenue decided to test the new computer system during the two weeks that taxpayers crowd in to pay their August real estate bills which are due by midnight Monday.

"We've improved our internal system (for keeping track of city revenue collections) but it is not improving our response time to customers," said Maureen Plummer, chief of collections.

Since it now takes twice as long to process an average payment -- four minutes instead of two -- taxpayers, many of whom are elderly, are standing in the hallways of the Munilcipal Center for up to an hour, instead of 10 minutes, as they did in the past.

"I've been coming down here for 20 years and I've never seen anything like this before," said 78-year-old Michael McKain, of Chevy Chase, as he joined 60 people standing in line Tuesday. "I usually walk right in."

Since Monday at noontime the line for paying all city bills has extended out of the cashier's office on the first floor, around the corner and toward on of three sets of front doors.

"The mayor has plenty of people in his office but there are only two (cashiers) down here," Allen Robinson, 69, of Ames Street NE, complained in a loud voice as he stood in the line Tuesday.

"We taxpayers don't have time to stand in line," he added, to the nodding agreement of people standing near him, "The traffic is heavy now and they should have extra people here." He said he had paid his taxes in person for 35 years.

Debra Datcher, 26, waited an hour to pay her mother's taxes and was nearing the cashier's office, but she worried about the elderly still in line.

"This is no way to treat taxpayers," she said. "Taxes are high and you deserve better service."

Three cashiers, instead of two, worked through the lunch hour yesterday.

Plummer first denied on Tuesday that the waiting resulted from the new computer system, although one of her employes had taped a handprinted note to a cashier's window saying "computer testing, please be patient."

Yesterday, she finally admitted the new computers are slower because cashiers are now entering more information so the city can keep better track of its money and because of internal problems with the new machines.

Sometimes the printing part of the new system will not validate tax bills, checks and money orders. Cashiers must continue to insert the documents into the computer until they are accepted, she explained.

In the past, cashiers simply rang up the payments on cash registers. With the new computers, four pieces of information must be fed into a computer terminal and then the bills and payments must be validated on a separate printer.

Across the hall in the car registrations office, officials returned to using a cash register yesterday because the lines were so long.

Tax bills can be mailed to the office, but many in the line said they had mailed payments in the past only to have the city government lose them.

Fay Lebowitz, who lives in Northwest Washington, said she normally mailed her payments until her mother mailed her water bill earlier this year and it was lost. She wanted to pay her real estate taxes in person and receive an immediate receipt, she said.

A Northeast man standing nearby said he had a similar problem. He paid his property taxes by mail in March (payments are due twice a year), but later received a notice that they were overdue. "They don't know what they are doing," he said holding the cancelled check in his hand to prove the payment.

After the 15-day testing period, Plummer said she will make a recommendation on whether the city should accept or reject the system.