In highschool how many unexcused absences can you have before you get legally in trouble?

Not legal advice: Unexcused absences can become a legal issue if a student has amassed enough to be considered habitually absent or “truant.” Truancy is a state issue and as such, laws and regulations vary by state.

Examples of how many unexcused absences define truancy in different states:
California: 3 full days or 3 absences of 30-minutes or more.
Connecticut: 4 days in one month or 10 days in one school year.
Illinois uses a formula to define a legally truant student; it works out to about 18 absences in one school year.
Louisiana: 5 or 10 absences depending on the school’s class schedule.
Nebraska: More than 20 days combined excused and unexcused.
Virginia: 5 days.

Once a student reaches the truancy limit it is the responsibility of a district official, such as a truancy officer, to contact the student’s parent(s) and the juvenile court system. A court may impose fines and jail time to students and/or parents.

Massachusetts passed the country’s first truancy laws in 1852.