If you have a trust then you have to file a return. This return is due 90 days after your December 31st year-end, which this year is March 31st. You cannot e-file the actual T3 return, only the T3 supplemental can be e-filed, so you have to mail the return or drop it in a CRA mailbox. Therefore, you should get the T3 return in the next couple of days and get it filed.
Principal Residence: New Tax Reporting Guidelines for Canadians
Learn More HERE