The Commission Rate is completely negotiable between the seller and the listing Salesperson/Brokerage Firm. The commission rate can be either a percentage of the selling price or a flat fee.
Gst is payable on the sales commission.
Remember that a real estate sales person does not invoice sellers or buyers for their expenses. Instead, they are paid a commission when the property sells.
Think of the commission as being really to parts: the listing portion that is paid to the listing agent/Brokerage Firm to cover marketing and advertizing cost, such as feature sheets, Virtual Tours, Sign fees, Open houses, advertizing in the real estate news, Mls, ect.
And the selling portion that is offered to the buyers representative to cover some of the expenses associated with showing homes to buyers, preparing and delivering offers, qualifying buyers to ensure they are legitimate buyers who can afford to purchase your home, ect.