Taxicab fares will go up Monday by about 10 cents a mile for passengers who ride District of Columbia cabs between Washington and places in Maryland and Virginia, including National Airport.

The fare increase, pushing the price of an interstate ride in an unmetered District cab up to the average cost of a ride in a metered suburban cab, was approved in an order circulated yesterday by the Washington Metropolitan Area Transit Commission. There will be no fare changes for rides entirely within the District.

Under the order, a direct five-mile ride from National Airport to the Mayflower Hotel in downtown Washington for a single passenger will rise from about $4.70 to about $5.10, plus a 50-cent airport dispatching charge, while a 27 1/2-mile ride from Dulles International Airport to the Mayflower will rise from about $22.40 to about $25.35. Prices may vary because of different routes drivers may use.

The fare for additional passengers in a prearranged group remains at 75 cents each, regardless of the length of a trip. Additional passengers not in groups are charged a full fare.

Fares charged for interstate trips in suburban cabs will continue to be the amounts shown on their meters, plus the same 75-cent charge for additional riders.

Under an interstate compact, the transit commission regulates the cost of taxicab travel only when it crosses state lines in the Washington area. The cost of travel within the District or within either adjacent state is set by the city or county government that licenses an individual cab.

Over the years, the commission has accepted for interstate trips the metered rates set by the suburban jurisdictions for local travel. Since taxi rates in unmetered District cabs are based on a city zone map, however, the commission had to set a mileage rate for out-of-city trips based on odometer readings.

The present fare for an individual passenger is $1.10 for the first half mile plus 40 cents for each additional half mile or fraction. The new fare after 4 a.m. Monday will be $1.50 for the first full mile plus 45 cents for each additional half mile or fraction. This means that the cost of the first full mile will be unchanged, while the cost of each additional full mile will rise by 10 cents.

William H. McGilvery, executive director of the commission, acknowledged that the change that will base the initial cost of hiring an interestate cab from a half mile to a full mile could cause some confusion for drivers and passengers alike.

For a five-mile trip such as the one from National Airport to the Mayflower, the 40-cent fare boost to $5.10 is an increase of 8.5 percent. For a 10-mile trip from downtown to, for example, the Bethesda area, the 90-cent fare rise to $9.60 is an increase of 9.7 percent. For a 15-mile trip to the Andrews Air Force Base area, the $1.40 fare increase to $14.10 is an increase of 11 percent.

The District's historic use of unmetered cabs has sparked frequent complaints about overcharges, expecially from airport passengers. The transit commission, for the first time in its 20-year history, recently ordered formal hearings starting next week that could lead to disciplinary action against two District cabdrivers accused of repeated overcharges.

The new fares were adopted after a transit commission inquiry to see whether interstate fares charged by District cabs had kept pace with metered fare increases approved by suburban jurisdictions since the last interstate fare rise in 1979.

In its order, the commission reported that current District interestate cab rates are tied with Price George's County for the cheapest rates in the region. The new rates will bring District rates up almost precisely to the regional average, exceeded only by cabs licensed by Arlington and Alexandria.