When you are renting a room, house or unit through Airbnb, there will be no GST applicable as it is considered to be the same as residential rent. But the income earned will need to be declared through the individual's income tax. This means that GST is not included and you do not need to register for GST.
When it comes to the rental expenses incurred that relate directly to the renting of that room or area, you are entitled to a portion of the tax deduction on them. This can include: internet, phone costs, water and power.
This changes when you provide accommodation in a manner like a hotel room or bed and breakfast and GST will have to be paid. This is because it is deemed as commercial property and with these types of accommodation are GST applicable. So, GST will need to be included.
Additionally, when you are an enterprise and you have a turnover of $75,000 then you are subject to GST. More commonly those who rent out a room would not be operating as an enterprise so this would not be relevant.
See: ICB Bookkeeping for Airbnb for more information.
Edited at 28 Sep 2017 02:36 AM GMT