Beginning July 1, families of four may earn up to $12,090, an increase of $1,100, and still be eligible for their children to receive free meals under the federal school lunch program. Children in families earning up to $17,210, a $1,580 increase, will be eligible for reduced-price meals (40 cents for lunch, 20 cents for breakfast). The new ceilings were announced last week by the Agriculture Department's Food and Nutrition Service and were based on increases in the Consumer Price Index.

About 23 million of the nation's 50 million public school children participated in the school lunch programs this year and 11.7 million received either free or reduced-price meals. About 90 percent of the nation's public schools take part in the lunch program and about 30 percent are in the breakfast program. The total federal subsidy for the school meal program will be about $2.5 billion this fiscal year and is estimated to hit $2.7 billion next year. Because of congressional tinkering with the eligibility formulas last summer, 1.2 million fewer children received free or reduced lunches this year than in school year 1980-81. Despite the increase in the income levels, the number of eligible children is not expected to change in the next school year.