Prince George's County Executive Lawrence J. Hogan is preparing a budget that will call for approximately $15 million more spending than last year but will lower property tax bills for most homeowners, according to sources familiar with budget preparations.

The budget of approximately $490 million is expected to cut the property tax rate from $2.68 per $100 of assessed valuation to $2.48 per $100. The tax bill reduction is the result of the tax-limiting TRIM county charter amendment approved by voters in 1978 that freezes the amount of property tax the county can collect.

Despite the restrictions on taxing, Hogan feels he can increase the budget and avoid severe cuts in programs and services because of the $14 million budget surplus and past cost-cutting measures in the county government.

Homes in the county are assessed at 45 percent of market value. As a result of the property tax reduction, the owner of a $60,000 home that was not reassessed this year would pay about $55 less in taxes than last year. For the owner of a similar home whose property was reassessed the reduction would average only about $18.

Hogan refused to discuss the tax rate yesterday but said the budget would reflect his priorities of assuring public safety and promoting the county's economic development, while decreasing the size of the county government by reducing the number of jobs.

The budget for police and fire protection will be increased by about $1 million, to $34.6 million, to allow for 33 additional police officers, bringing the total number of police to 873, the highest number since 1977, Hogan said.

In addition, the police department will be authorized to hire 27 "public service aides," civilians who will do work currently assigned to police, such as directing traffic and gathering evidence. "The aides will free up other officers," said Hogan. "It'll be good entree to the police department, a prelude to going into the recruit class."

Police union president Laney Hester said Hogan's proposed additions to the police force constitute "a tax cut at the expense of the citizens safety," and said the county needed "a minimum" of 75 to 100 more officers.

The biggest item in the proposed budget will go to education, which accounts for $296.1 milllion, about $9 million more than the schools received last year.

The school board had requested a raise of $22.8 million, which would have included $15 million to fund a cumulative salary increase for teachers of 9.1 percent.School board spokesman Brian J. Porter called the proposed $9 million "not enough to even maintain the programs at the level they're at now." He would not comment on the probable effect on teachers' salaries, saying the school board has not signed a contract with the teachers yet.

Hogan said he does not plan any big cuts in county programs, although he will continue to reduce the number of county workers through attrition. The County Department of Economic Development would get the biggest percentage increase under Hogan's proposed budget, an increase of about $175,000. "That's money well invested," said Hogan. "The department creates jobs and taxes and returns a dividend" by encouraging businesses to settle in the county. Last year the council slashed the department's budget.

Department heads submitted their proposed budgets to Hogan earlier this week. Hogan has not made decisions on many of them, but he has given them limits to follow. He must submit his proposed budget to the County Council by March 31, and the council must decide on whether to adopt or modify it in May. The council sets the tax rate in June.