The Montgomery County Council reduced the current property tax rate for county homeowners from $2.06 to $2.04 per $100 of assessed value yesterday, but rising property assessments will increase tax bills an average of 3.1 percent among the county's three assessment districts.

For a house with a current $100,000 market value, next year's tax bills will rise between $24 and $107, depending upon which assessment district a taxpayer lives in, officials said. That would bring the average tax bill on the house to between $1,499 and $1,806.

The overall rate decrease for the fifth year in a row was due primarily to the good performance of other revenues the county takes in, an official said.

Property taxes make up about 40 percent of the county's revenue sources, which also include income and sales taxes.

The tax rate unanimously approved by council members will maintain Montgomery's $968 million operating budget next year. That will leave intact a $22.7 million surplus of which $18 million will be in the general fund and $1.5 million will be in the mass transit fund.

In addition to the 2 cent reduction in the property tax rate, there was a 1 cent reduction in the mass transit tax from 23 1/2 cents to 22 1/2 cents. These two taxes are required of all county homeowners.

Rates for six special districts, including recreation, sanitary and Maryland-National Capital Park and Planning Commission districts, also went down by 1 to 2 cents or remained the same.

The average increase of 3.1 percent in tax bills is less than the area's current 4.5 percent rate of inflation, noted council member Neal Potter.