The Arlington School Board has decided to seek legal advice on the possibility of charging tuition to families of military children attending county schools, if the county does not get its anticipated share of federal impact aid funds this year.

Though the board did not take any official stand at its meeting earlier this month, most members appeared to be leaning in favor of such a move if all aid is lost.

About 235 children of military personnel who live and work at the Army's Fort Myer in Arlington attend county schools, according to school officials.

Impact aid is money given to localities to compensate them for lost revenues from untaxable federal property within their boundaries.

Congress has not yet adopted a distribution formula for impact aid, although total funds for the program have been cut about 37 percent and the Reagan administration is seeking an additional cut of 26 percent.

Last week, school board Chairman Claude M. Hilton said he believes the board should delay any action until Congress makes a final decision on the distribution formula.

The Arlington County Board has set aside a $1 million contingency to cover losses in federal aid this fiscal year, including $500,000 to compensate for losses in impact aid. Those funds, however, would leave the school system $429,000 short if it loses all the anticipated impact aid, set at $929,000 in this year's budget. And this month, the County Board put the school board on notice that it may not get the full $500,000 budgeted for impact aid losses.

On concern in arlington is a proposal before Congress to limit impact aid to jurisdictions where at least 20 percent of the students live on a military post. The 235 Fort Myer children make up only 1.5 percent of Arlington's total school enrollment of 14,757.

One Northern Virginia school system, Fairfax County, already has notified military personnel that it plans to charge tuition to familes of military children, if impact aid falls below 50 percent of the county's antcipated funds.