The Collaborative International Dictionary of English v.0.48:

nonexempt \nonexempt\ adj.
   1. Not exempt; subject to (some specified) rule. Opposite of
      exempt. [Narrower terms: liable to(predicate);
      subject, subject to(predicate)]
      [WordNet 1.5]

   2. Specifically: (U. S. Labor Law) Not exempt from the
      provisions of the fair labor practises act; -- a term
      applied mostly to persons who are hourly employees, who
      are required by law to be treated in certain ways. Many
      salaried and management personnnel are not covered by the
      law and are therefore exempt.
      [PJC]

WordNet (r) 3.0 (2006):

nonexempt
    adj 1: (of goods or funds) subject to taxation; "taxable
           income"; "nonexempt property" [syn: taxable,
           nonexempt] [ant: exempt, nontaxable]
    2: (of persons) not exempt from an obligation or liability [ant:
       exempt]