Metrobus fares will rise Monday for more than 75,000 daily riders in the Maryland and Virginia suburds in a move designed to add $3.5 million a year to fare collections and expected to discourage 5,000 bus riders from traveling each weekday.

District of Columbia fares will not go up Monday from the present 40 cents level. However, the Metro board will hold a second hearing in the city Monday evening on a proposal to raise the rush-hour D.C fare to 50 cents starting July 1.

The fare increase that goes into effect Monday in the suburbans was approved Feb. 24 by the Metro board. At that time, the board ended its previously policy of having equal fares for similar trips in Maryland and Virginia, and decided to impose steeper increases on Virginia riders.

This was done at the insistence of suburgan Virginia political officials concerned about the rising share of local tax bills that are going to pay subsidies for Metro deficits. The deficit for the entire metropolitan area this fiscal year is budgeted at $54.8 million.

Starting Monday, Virginia rush-hour riders will pay 10 to 30 cents more than the present fares, with the top fare for the longest ride between Washington and communities west of Fairfax City going from $1.20 to $1.50 each way.

The largest group of Virginia riders, those traveling between Arlington or Alexandria and Washington, will pay 90 cents, compared with the present fare of 75 cents.

With this increase, residents of the two Virginia communities will pay more than twice the fare a Washingtonian pays for a city bus trips of equal or longer distance. The District government makes up the difference from tax revenues.

Maryland rush-hour riders will pay 5 to 20 cents more than the present fares, with the longest ride - to and from such outlying communities as Bowie-Belair and Gaithersburg - going from $1.20 to $1.40.

The largest group of Maryland riders, those traveling into Washington from such communities as District Heights, Hyattsville, Takoma Park, Silver Spring and Bethesda, will pay 80 cents, only 5 cents more than at present.

For fare-collection purposes, the rush-hour is from 6 to 9 a.m. and from 3 to 6:30 p.m. on weekdays.

In non-rush hours and on weekends, the fare from anywhere in suburban Virginia into downtown Washington will rise from 60 cents to 70 cents. There will be no increase of the 60 cent fare from Maryland.

Rush-hour fares for trips entirely within Maryland will range from 50 cents to $1.10. Rush-hour fares for trips entirely within Virginia will range from 50 cents to $1.30. The non-rush fares for travel between all points within both states will stay at 40 cents.

Following is a detailed explanation of the increased fares for rush-hour trips between the suburbs and Washington:

Virginia - if your present fare is 60 cents, it will be 70 cents; if it is now 75 cents, it will be 90 cents; if it is now 90 cents, it will be $1.10; if it is now $1.05, it will be $1.30, and if it is now $1.20, it will be $1.50.

Maryland - if your present fare is 75 cents, it will be 80 cents; if it is now 90 cents, it will be $1.00; if it is now $1.05, it will be $1.20, and if it is now $1.20, it will be $1.40. (virginia has one more zone than Maryland, for the area around the Pentagon, with a minimum fare currently lower than Maryland's.)

The hearing Monday on the D.C. bus fare increase, along with proposals for Metro's future bus-rail transfer and fare plan, will be held at 7:30 p.m. at Ballou High School, 4th and Trenton Streets SE. Other hearings on the plan will be held at 7:30 p.m. Tuesday at Kenmoor Junior High School in Ladover, Md., and 7:30 p.m. Wednesday at Lee High School in Springfield, Va.