underassess

under- +‎ assess

underassess (third-person singular simple present underassesses, present participle underassessing, simple past and past participle underassessed)

1. (transitive) To assess at too low a value.
   • 1988 December 9, Ben Joravsky, “Property-tax assessments rise; north siders are revolting”, in Chicago Reader‎:

     So a school district whose property is underassessed will get more state aid than it deserves.

• assuredness