A $13.9-million real estate tax reduction bill, described by its sponsor as the most significant in District of Columbia history, was approved yesterday by the D.C. City Council's finance and revenue committee.

Enacted - as expected - by the full council, the measure would cut $295 off the present $732 in taxes due from the typical owner of a $40,000 home. It would cut $349 off the $1,464 due from the owner of an $80,000 home.

The measure would exempt $9,000 of the value of each owner-occupied home from taxation, raising the figure from the present $5,000. iIt also sets the stage for cutting the tax rate for owner-occupied homes from $1.83 to $1.57 for each $100 of assessed valuation.

Taxes on large apartment buildings and business properties would stay at $1.83. The actual tax rate will be set formally by the council next month.

Committee approval of the bill came by coincidence, one day after Californians voted overwhelmingly to curtail local government powers to levy real estate taxes. Assessments in the District, as in California, have soared in recent years. They have doubled here in five years.

The tax cut bill, sponsored by Marion Berry (D-AT large), the committee chairman, embodies festures proposed by both Berry and Mayor Walter E. Washington, who are rival mayoral candidates.

In addition to the real estate tax cut, Washington had proposed a $10-a-person income tax credit for members of families that have earnings of less than $10,000 a year. The committee instead endorsed Barry's proposal to expand the current "circuit breaker" tax credit to cover families, renters as well as homeowners, with incomes up to $20,000 instead of the present $7,000 limit.

Action by the full council is expected during late June and July, making the cuts apply to tax bills that will be mailed about Aug. 15 with the first installment due Dept. 15.

leo J. Ihrig, deputy director of the D.C. Department of Finance and Revenue, told the committee yesterday that he experts a severe problem of identifying homeowners who qualify for the lowered tax bills.