Sadly, if he isn't required to file a return no one can make him even if he would get a refund if he did file. However, if his income was high enough to be required to file AND the IRS figures he would owe taxes then the penalties & interest is piling up ... and one day it will catch up with him.
Now if he is self employed and fails to file a return that is considered tax evasion and that is something you can turn him in for ... <a rel="nofollow" target="_blank" href="
https://www.irs.gov/individuals/how-do-you-report-suspected-tax-fraud-activity">https://www.irs.gov/...>
