If customers and clients are likely to gather at your house in substantial numbers, you may well be in breach of planning regulations. Your council could order you to cease trading or fine you for every day that you continue to trade against their order. Similarly, if noise from your house becomes excessive, you face a similar fate. Under the Development Act 1993 (SA) 'home activities' are usually allowed in a residential zone and it is possible that these home activities can be business activities if they use an area of less than thirty square metres and do not detract from the amenity or quality of the area. However it is best to check with your local council. If a house is used as an office and a home mortgage is being paid, it is possible to obtain tax deductions for a portion of the interest paid. Deductions can also be claimed for a portion of council rates, water rates, strata rates, telephone expenses and building insurance premiums. A tax agent should be consulted for advice on home tax deductions.