You must be at least 16 years old in order to take the ASVAB test. If you are a junior or senior in high school, then you will be taking the test as a part of the Career Exploration Program also known as the Student Testing Program. Test scores are valid for two years, and you must wait one calendar year to retake the ASVAB. You must wait an additional calendar month to retest again. After that, you must wait six calendar months to retake the ASVAB. There are no limits to the number of times you can take it.
The “Student” ASVAB is a career assessment tool that can help you identify which career areas best suit you. Because this is an aptitude test it doesn’t just tell you what you are currently good at, it will also tell you what you may be good at learning. When enlisting in the military, scores are used to determine the most appropriate services to join and the most best suited jobs within that service. The higher the test score, the more career options that are available. In addition, the score can directly affect eligibility for bonuses and money for school.
http://official-asvab.com/index.htm
The United States armed forces are well aware of the fact that money may discourage many young and talented individuals from joining the military, so they have been offering the ASVAB examination for free.
https://www.military.com/join-armed-forces/asvab https://www.asvabprogram.com/pdf/ASVAB_CEP_Counselor_Manual.pdf https://www.asvabprogram.com/faq