After you register GST/HST account and become a GST/HST registrant, you generally have to charge and collect the GST/HST on taxable supplies (other than zero-rated supplies) you make in Canada and file regular GST/HST returns to report that tax.
You can claim ITCs on your GST/HST return to recover the GST/HST paid or payable on purchases and expenses you use, consume, or supply in your commercial activities.
When you complete your GST/HST return, deduct your ITCs from the GST/HST you charged your customers. The result is your net tax. The net tax is calculated as the following:
Net tax = GST/HST charged – ITCs
If the net tax is positive, you have to remit the amount to the Canada Revenue Agency (CRA).
If the net tax is negative, you can claim a refund for the amount.