Citizens' groups in Prince George's and Montgomery counties said they will file petitions today that would force November voter referendums on proposals to freeze property tax collections in Prince George's and slash tax rates in Montgomery.

The Prince George's County group expected to have 15,000 signatures by this morning in support of a charter amendment that would freeze total annual property tax collections at this year's level - projected to be $140 million.

Among the signatures will be that of County Executive Winfield M. Kelly Jr.

In Montgomery, a citizens' referendum committee said it would have well over 15,000 signatures supporting a charter amendment there when petitions are to be filed this morning, the last day for placing charter questions on the November ballot. Some 10,000 valid signatures are required in both Prince George's and Montgomery to force election officials to plce the measure on the ballot.

The Montgomery citizen's charter amendment would reduce the general fund property tax rate by about 15 percent from $2.60 to $2.25 for each $100 of assessed property value, according to supporters.

Meanwhile, the Montgomery County Council will vote this afternoon on whether to submit its separate - and less drastic-charter amendment to voters.

To council measure would require that five of the seven council members approve the annual budget - instead of the present requirement of four - in years in which the budget's percentage increase exceeded the percentage increase in the consumer price index for the Washington area.

The council amendment is being advanced as an alternative to the proposed tax cut, which Montgomery County officials believe would reduce revenues far more than the sponsors of the tax rollback had planned.

Montgomery council member John Menke said yesterday that a study by the county attorney's office had determined that the tax cut amendment proposal had been unintentionally worded so as to require reductions in several supplementary property taxes, in addition to the main general fund tax.

Consequently, Menke said, county projections indicate that the amendment would really cut the tax rate by almost $1, instead of 35 cents.

While the citizens' committee that gathered the signatures, called the Tax Relief in Montgomery Committee (TRIM) projects a reduction of about $30 million in county revenues as a result of their proposal, county figures project a drop of $90 million or more.

Montgomery TRIM chairman Karl Schlotterbeck insisted yesterday, however, that the county study had been "unofficial" and that the proposed amendment's wording would not result in a change in the supplemental taxes, which are used to support park funds, recreation and other programs and are responsible for increasing the total tax rate in Montgomery to from $3.37 to $4.20 for each $100 of assessed value.

"The amendment is absolute, it's constitutional, it's correct and it's responsible," Schlotterbeck said. "The bureaucracy in Rockville is putting out a lot of scare stories. They tried that in California on Proposition 13, and it didn't work."

Schlotterbeck said that more than 200 persons are now working for his group as volunteers, and that a fundraiser was being planned to help mount a campaign to pass the proposed amendment.

If both the TRIM and Montgomery council proposals are approved for the Montgomery ballot, voters could approve both of them.

The Prince George's County referendum drive has been led by two independent Democratic candidates for District 23 delegate seats, William Goodman and David Bird, and has also been named TRIM - in this case, Tax Reform Initiative for Marylanders.

Because the proposed property tax collection freeze would be permanent, Bird said, property tax bills would gradually decrease in the county as new homes are built.

The county could make up for property tax revenues lost to future inflation by creating a separate tax division for commercial - as opposed to residential - property, Bird said.

The proposed amendment contains a provision that if commercial property is taxed separately, taxes on commercial property would have no ceiling.