D.C. City Council member John A. Wilson, seizing the initiative on a key political issue in the city, introduced legislation yesterday to give all city homeowners a 10 percent property tax rebate this year to grant 20 percent income tax rebates to persons earning $15,000 a year or less.

Wilson's legislation also would return all property taxes paid this year by owners of subsidized, low-income housing projects.

The tax relief program would cost the city about $20 million, Wilson said. He said funding for the program could come from a $40 million balance on the city's books at the close of the fiscal year that ended Sept. 30.

Rising property taxes that result from skyrocketing housing costs and a general increase in the cost of living in the District have been lively political issues in recent city campaigns. Many have said that low-and moder-ate-income residents are being forced out of Washington by the increased expenses.

Wilson, chairman of the council's finance and revenue committee, proposed that all owner-occupants of single-family homes or buildings of five units or less -- about 65,000 people -- receive a rebate equal to 10 percent of their 1977-1978 property tax bill.

For the owner of a $50,000 home, the rebate would be about $78, according to Wilson aides. That portion of the three-part program would cost the city between $5 million and $6 million.

The second part of Wilson's plan would grant rebates equal to 20 percent of the income taxes paid for the 1977 tax year to all persons filing single returns with an adjusted gross income of $15,000 or less or to couples filing joint returns with adjusted gross incomes of $30,000 or less.

That rebate would be about $71 for a single person with an $8,000 income and more than $250 for a couple with a joint income of $20,000, according to Wilson aides.It would cost the city an estimated $11 million.

The thrid portion of Wilson's plan would provide full property tax refunds to owners of 68 federally subsidized, nonprofit housing projects throughout the city.

The portion of the program would cost $2 million to $3 million, aides estimated. None of that money would be required to be returned to tenants in the $21,000 units affected. But, Wilson said in a prepared statement, it would help the apartment owners meet the costs of rising utility bills and perhaps avoid increases i rent.

Brigid Quinn, exective assistant to Wilson (D-Wared 2), could not say yesterday what the chances were for approval of the legislation, which will undoubtedly be assigned to the finance and revenue committee.

If the council does not become embroiled in a bitter floor fight over the proposals, Quinn said, the tax rebate program could be working by this summer.

The $40 million city book balance from which funds for the progrm are to come was first disclosed Dec. 11 by then-outgoing mayor Walter E. Washington, who said it was the largest year-end cash balance in at least 10 years.

Washington recommended that the city use the money to establish a "working capital fund to be used to meet the city's cash-flow requirements."

Wilson said yesterday, however, that since the cash balance came about in part because of $20 million in income and property tax revenues that exceeded city estimates. the money should be returned to taxpayers.

In addition to opposition on the council, two other obstacles could hinder the tax refund program. In the recent past, Congress has, in effect, tied the level of the city's federal payment to the budget surpluses created by unexpected revenues. When the city raised excess revenues, the federal payment has been reduced correspondingly.

Secondly, Mayor Marion Barry, who has yet to propose any use for the "surplus," has had his top aides examining the city's books to determine whether such a surplus really exists or is merely an illusory balance because of bills that still must be paid.

Ivanhoe Donaldson, Barry's general assistant. declined comment yesterday on Wilson's proposals.