There are tax advantages in investing in property, but these should be looked at as "cream on the cake."
The main consideration should be the fundamentals of investing in an asset with due consideration being given to income streams, capital growth. and overall rate of return on the investment.
Negative gearing is the term used to describe the shortfall between an income stream and expenses incurred in holding an asset which may reduce your taxable income.
To calculate the tax deductible amount estimate the income and deduct estimated expenses.
Income may be derived of rent received.
Deductible expenses would include interest paid on loans to purchase the asset, borrowing costs, rates, insurance, land tax and repairs.
If the expenses exceed the income the shortfall will be tax deductible and hence reduce your taxable income.
To use an example, if the negative gearing is $10,000 p.a. and you are in the 37% tax bracket, then you will reduce your actual tax payable by $3,700.
The larger the negative gearing and the higher your tax bracket, the greater will be the reduction in the tax you pay on your taxable income.
Remember the whole purpose of investing in an asset is to maximise your capital growth and income return, not to merely maximise your tax deductions.
The investment needs to stand on its own two feet.