underreport

verb

1. To report a number falsely, making it smaller than it ought to be, especially to do so intentionally

   “March 9, 2007, Lara Jordan, Associated Press, Audit Slams FBI Use Of Patriot Act The FBI underreported its use of the USA Patriot Act to force businesses to turn over customer information in suspected terrorism cases, according to a Justice Department audit.”

2. As a group, to report something less frequently than it actually occurs

   “Women tend to underreport rape.”