The Prince George's County Council of PTAs is planning to launch a petition drive to modify TRIM--the controversial 4-year old charter amendment that limits the amount of property taxes the county can levy.

Although final working of the petition and details of its circulation have not been worked out,Diana McCusker, president of the PTA council, said she hopes to win support from the Prince George's Chamber of Commerce and the Board of Realtors when the campaign begins later this month. At least 10,000 signatures must be collected by July to place the proposed amendment on November's ballot.

Democratic Councilman Parris N. Glendening, so far the only person to declare openly his intention to run for county executive this year, said this week he will "stake my political career" on efforts to modify TRIM to prevent cuts in county services. He said he "will be more than willing to lend whatever support I can to an effort that makes a reasonable modification."

TRIM restricts property tax revenues to their 1979 level of $144 million. As property assessments increase, the tax rate must be lowered to keep revenues at or below $144 million. Critics blame TRIM for depriving county residents of essential county services, while supporters credit TRIM with keeping property taxes at reasonable levels. TRIM stands for Tax Reform Initiative by Marylanders.

The new petition being formulated will involve a formula raising the property tax revenue limitation of $144 million, McCusker said.

The PTAs, Chamber of Commerce and Board of Realtors attempted to put a TRIM referendum on the ballot two years ago, but fell about 2,000 signatures short of the 10,000 they needed. Paul Feller, vice president of the Board of Realtors, said this week that his organization has no con crete plans to join a petition drive. "It remains to be seen" if the public support is there, he said.

The Realtors, concerned that too many county services may be cut because of TRIM limitations, support a modification that would exclude property taxes on newly constructed homes from being counted in the $144 million limit, Feller said. This would have been accomplished by the amendment proposed two years ago, and Feller said Realtors still are interested in a similar plan.

That modification would not have increased current homeowners' property taxes. Another modification under discussion would allow property tax revenues to increase in relation to cost of living increases.

"This time, this year, we think most people can see the effects of TRIM," said McCusker. "The roads are deteriorating, . . . the libraries are not offering the same services. . . . We need to allow ourselves flexibility in times of great inflation."

Four years ago, Glendening said, he opposed TRIM, but did not take a firm stand on it. "Some of my advisers and supporters on the executive race have told me to either be noncommittal or not out front," he added. "It isn't popular. However, I feel so strongly on this. . . . What good would it be to be an executive when all you're doing is cutting every single service that is essential?"

The Fraternal Order of Police, which has long opposed TRIM ("a noose around the neck of P.G. county," said FOP President Laney Hester), is unlikely to join the PTAs' effort. "It's not worth pursuing anything if you don't have a chance of getting it," Hester said. "I don't know if the citizens are aware. We haven't really felt the full impact of it. But the day of reckoning is coming. It's going to be dramatic when it comes. You can't operate in 1982 on 1979's budget."

John Sisson, president of the National Educators' Association of Prince George's, which represents most county school teachers, said his union will support the PTAs. This year's petition has "much more of a chance," he said. "People are seeing the negative effects. The obvious ones are potholes in the roads. The less obvious ones are school funding."

Del. David Bird (D-Hyattsville), one of the two originators of the original TRIM petition four years ago, said he expects many assaults on TRIM this spring, when the drawing up of annual budgets coincides with preparations for November's elections.

"I anticipate it's going to be an issue this year," he said. "I'm ready to debate it. . . . I'm anxious to join the fray, get in the debate."

Bird said he believes the county will not need additional sources of revenue for a few years, but when it does, he supports a "tier tax." He said he is working on a report on tier tax system, which would tax different types of property at different rates. This system is used in the District of Columbia.

Bird also said TRIM has been "interpreted too drastically," and used as a basis for "budget cutting" rather than getting more tax money from other sources.

TRIM repeatedly has been cited by Prince George's County Executive Lawrence J. Hogan as the reason programs cannot receive the funding their advocates demand. The $336,554,972 school budget proposed last month by Superintendent Edward J. Feeney, for example, is impossible to meet within TRIM restrictions, according to the county budget office.

Hogan said that meeting the budget would mean "at the very least, a 17-cent increase in the property tax rate and laying off a minimum of 1,200 employes in county agencies."

Hogan, in a letter to School Board Chairman Doris A. Eugene last week, said he concluded that "the school system has not taken seriously this mandate of the people." He speculated that the school system "thinks that proposing astronomical spending increases and predicting doom if they are not adopted is the best way to achieve TRIM's repeal."

TRIM, itself the product of a petition drive, was overhelmingly supported by county voters in 1978. It was passed in the wake of California's tax-slashing Proposition 13 in 1978. It was supported by then county executive Winfield M. Kelly, and by Hogan, his election rival.

TRIM was billed to voters as a way to reduce property taxes and thus limit government spending. Spending still rose, but less quickly than the rate of inflation. Since TRIM was passed, the county has reduced the rate of property taxation by 21.3 percent, from $3.31 for every $100 of assessed value to $2.60, because of increases in assessed value of properties.

The county's income from property taxes fell last year to $131.2 million. This year, it is expected to be $133.9 million, $10 million under the $144 million ceiling.

Bird complained that the TRIM amendment drafted by the PTA and Chamber of Commerce two years ago would not have helped homeowners. The amendment would have done nothing to relieve the tax burden of homeowners, who pay two-thirds of the county's property taxes, he said. Bird said the county should tax business and commercial property more heavily, and rely more on income tax, to relieve the burden on residential property owners.

"I do believe that we need what Winnie Kelly called the tier tax," Bird said. Under this system, two or three different tax rates would be in effect, allowing the county to set higher tax rates on business and commercial property and a lower rate for individual homeowners.