In a November 6, 2014 Technical Interpretation (2014-0530991E5, Godson, G.), CRA discussed the liability of an employer who fails to withhold taxes as required under Subsection 153(1) in respect of taxable benefits. CRA noted that the payor is only liable for penalties and interest pursuant to Section 227 in respect of Canadian resident employees. However, for non-resident employees, the employer is also liable for the taxes which were required to be withheld (Subsection 227(8.4)).
For further information see VTN Monthly Tax Update Seminar, Issue No. 402