GST / HST is due January 31st for the reporting period October 1st through December 31st.
And you don't want to file late because of tax penalties.
You should already have received a personalized GST/HST return form from the Canada Revenue Agency (Form GST34, Goods and Services Tax/Harmonized Sales Tax Return for Registrants).
If you haven't gotten one, or if you've lost it, call the Canada Revenue Agency at 1-800-959-5525 to get another one.
Filling out the form and filing it is pretty straightforward, but if you have questions regarding GST/HST, check out my Answers to Common GST HST Questions. The answers cover everything from which goods and services are GST/HST exempt and how to calculate GST/HST through Input Tax Credits and payment methods.
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