A claim that an agent did not pay taxes and make payments does not state a claim as a defense to nonpayment unless the nonperformance incapacitated the principal in that respect -- a high bar.
http://media.ca8.uscourts.gov/opndir/18/09/172326P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.