The Prince George's County Council will begin reviewing the proposed 1978 budgets for major county departments and agencies tomorrow. For the first time, the Council is requiring department and agency heads to justify the continued funding of many of the programs now budgeted by the county.

The new budget review process is an attempt to use the principle of zero-based budgeting by which the effectiveness of a program will determine whether it merits continued funding, Councilman Parris N. Glendening said. Glendening is chairman of the Council's special committees on governmental performance and fiscal policy.

In the past, the Council decided on cuts or additions by evaluating the line items that show requests for personnel and equipment.

"What the Council would never get would be a picture of the total cost to the county of a particular program," Glendening said.

Directors of county agencies and departments - and the school board - will be required to answer specific questions about how efficiently their current programs are run and how economically they have county funding in the past.

For example, the Council has asked the school board to report all properties leased from the private sector and to justify these rental costs.

The police department will be asked why sworn officers are used to perform desk work that could be done by civilians and how the department can cut down the amount of time officers now spend filling out forms, Gledening said.

The Council also intends to review the county-funded education incentive program that pays for courses for police officers - even those not related to public safety. By earning college credits, an officer can increase his or her pay base.

Department heads must respond in writing to the Council's questions at budget work sessions. The Council will begin reviewing budgets tomorrow with work session on the budgets for the county executive's office and the department of hospitals.

"The budget sessions this year will be accountability sessions," said Council ChairmanWilliam Amonett.

Gledenuing said the Council plans to work within the $118.7 million budget that conty executive Winfield M. Kelly. Jr. has proposed. By eliminating some programme no longer needed, the legistlative said they may be able to reduce that budget and "start working in the direction of reducing the property tax a little bit," the councilman said.

The county executive's proposed fiscal 1978 budget would hold the tax rate at the current $3.37 per $100 of assessed valuation.

In addition to the school board and major county agencies, the Washington Suburban Sanitary Commission will also come under special budgetary review this year.

The Council will vote on the entire country budget May 13.