D.C. Mayor Walter E. Washington signed into law yesterday emergency legislation that will grant owners of single-family homes, members of housing cooperatives and some renters property tax credits on taxes due to the city Sept. 15.

Under the law, owners of single-family homes would receive an automatic $109 property tax credit through an exemption of the first $6,000 of a home's assessed value.

Housing cooperatives will receive an exemption of 12 per cent of the apartment building's assessed value rather than a $6,000 per unit exemption.

The new law also provides property tax credits for elderly, blind and disabled renters and homeowners who earn less than $20,000 a year. The tax credits for renters are based on a formula devised by the City Council, which calculates that about 15 per cent of a tenant's rent goes toward a building's property taxes. Tax credits for elderly, disabled and blind homeowners whose incomes are $20,000 a year or less are in addition to the credits granted to all homeowners.

The mayor also released yesterday an updated listing of 1,553 vacant, privately owned buildings in the District. By making the list public, the city government hopes to stimulate housing renovation. A spokesman for the mayor said that another listing of vacant, city-owned houses will be released in the future.

The emergency tax relief law, which provides greater relief to low-income homeowners than to upper-income homeowners, does not guarantee that any homeowner in the city will pay less in taxes this year than last.

In many residential neighborhoods, property tax assessments have soared, requiring homeowners in those neighborhoods to pay a larger tax increase than the -109 credit they will receive.

Housing cooperatives will recieve a property tax credit of 12 per cent of their buildings' assessed values rather than a $6,000 credit for each apartment within the cooperative, even though unit owners are considered homeowners.

When the emergency bill was debated in the City Council recently, Council members were concerned that if cooperatives got a $6,000 per unit exemption - cooperatives, which share taxes and other costs, might get a bigger tax break than the owners of single-family homes.

The mayor said that the $6,000 exemption for single-family homes will be relected in property tax bills to be mailed later this month. After deducting the $6,000, homeowners will pay taxes based on the city's cufrent rate of $1.83 per $100 of a home's assessed value.

The District's 66 cooperatives, however, will not receive their tax credits on their next tax bills. They will receive a refund later this year after they pay taxes due Sept. 15, the mayor said.

The updated list of vacant, privately owned housing in the city includes about 600 vacant buildings catalogued in another list published last October as well as about 800 additional vacant buildings.

About 25 per cent of the buildings listed here in the Shaw urban renewal area and in other sections of Northwest east of 16th Street.

Of the 1,553 buildings identified in the listing, 1,146 are single-family houses, 99 are two-family houses, 237 are apartment houses with a combined total of 1,421 units, 41 are rooming houses and 30 buildi ngs are for mixed commercial and residential use.