You may recall there are now two ways of claiming the cost of the business portion of premises used partly for business and partly private. You will be used to the old method of taking a share of power, maintenance and so on.
The new method is split into two parts. The Commissioner advises a square metre rate for all expenditure except mortgage interest, rates or rent. The square metre rate set for 2018 financial year is $41.10 per square metre. Claim the interest and rates (or rent) in the same way as usual. It would seem those renting have an advantage as they are not likely to have the same sort of repairs or maintenance costs. They may, therefore, be better off using the new method.
The business portion of the house has to be an area which is primarily used for business purposes.