Call the school's front office and ask to report free lunch fraud. Don't describe the circumstances of your report at this time.
Ask to be transferred to a principal or the cafeteria manager if the front office is unsure how to direct your call.
Repeat that you would like to report free lunch fraud.
If you are transferred again or asked to call back later, remain patient. It may be that no one has been clearly assigned the role of investigating suspected free lunch fraud.
When you do speak to the person prepared to hear your concern, carefully explain the fraud as you suspect it.
Explain who you are and how you have come in contact with the family you are accusing of fraud. Honestly explain any personal entanglements with the family you suspect, such as custody battles or divorce. You might be the best person to report fraud despite a conflict of interest.
Suggest that the school ask the parents to verify the income they reported on their application. The National School Lunch Program requires school districts to verify a small percentage of applications each year, and the school should have an appropriate letter and form on file.
Hang up, and accept that your role in this investigation of school lunch fraud is over. Any findings of fraud or changes to free lunch enrollment will remain confidential.