Important Dates for Businesses:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/menu-eng.html
GST / HST:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/gst-tps/dts-eng.html
PAYROLL:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/pyrll-eng.html
IMPORTANT DATES FOR CORPORATIONS:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/crprtn-eng.html
RETURNS:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/rtrns-eng.html
SLIPS AND SUMMARIES:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/slps-eng.html
PAYMENTS:
http://www.cra-arc.gc.ca/tx/bsnss/tpcs/ll-dts/pymnts-eng.html
INTEREST & PENALTIES:
http://www.cra-arc.gc.ca/tx/ndvdls/tpcs/ncm-tx/ntrst/menu-eng.html