Washington lost more than $900,000 in revenue during the first six months of 1976 because the city charged the majority of its public housing tenants incorrect rents, according to a U.S. General Accounting Office report obtained yesterday.

Some were charged too little, others too much, the report said with the net effect being the revenue loss.

In addition, the GAO report said that the city at the same time lost what could be a "substantial" amount of money by not charging enough rent for properties it owns in urban renewal areas.

GAO said it could not determine the rental loss because of "poor records," but noted that the city itself has estimated that it loses about $800,000 annually in parking lot rents in urban renewal areas alone because rents are too low.

The GAO report said the city needs to improve its rent-setting system in order to increase rental income, reduce federal subsidies, and provide equitable treatment to tenants.

The $902,000 loss in rents from public housing tenants occurred, the report said, because the city used a 1971 rent schedule to set rents, delayed processing rent changes for an average of about six months, and was ineffective in verifying tenant income, among other things. About 60 percent of the tenants were charged incorrect rents, it found.

That revenue loss was almost one-fourth the $4 million the housing department collected in rents during the six-month period.

The federal agency also called the city's utility payment policies "inadequate." The city paid electricity and gas bills for about 150 tenants who should have paid their own bills, and improperly paid electricity charges for 18 tenants who received utility allowances during those six months, the report said.

The report also said the city lost rental revenues in urban renewal areas because it did not examine rents periodically to determine whether they were still appropriate, did not efficiently set and adjust rents of temporary tenants, used outdated data in establishing rents, and did not have an effective system to make sure that rents did not exceed 25 per cent of tenant incomes.

By examining 100 randomly selected residential and commercial tenants, the auditors found that most rents had remained unchanged for a number of years.

City housing director Lorenzo W. Jacobs Jr. wrote a memo to the mayor last January, commenting on the GAO findings and recommendations. Jacobs wrote that his department has "taken steps" to address the federal auditors' recommendations.

Those steps include improving practices and policies for setting rents and utility allowances, and improving record-keeping, Jacobs wrote in the memo.

City housing officials declined to comment yesterday until they had seen the final GAO report.

The city, facing ever-increasing utility increases, began last September to impose a surcharge on public housing tenants who had freezers, clothes dryers, air conditioners, and more than one refrigerator in their homes and apartments.

During September, $12,307 was collected, and a city housing property management official, Welvin Goodwin, said more was expected to be collected each month after more complete records were put together on who owned extra appliances. Families were charged, for example, an extra $7 a month for utilities if they had a frost-free freezer and $17 a month if they had an air conditioner.

The city also began a study last fall on possible installation of individual meters in public housing units. Some units already are individually metered. Goodwin said yesterday the study has not been completed.