Please note that the following is general financial advice, and does not constitute personal financial advice - I haven't taken into account your personal personal objectives, financial situation or needs.
You can save money by taking out private health insurance when you earn over $90k p.a. When you go above this amount, you are forced to pay the Medicare Levy Surcharge, which varies between 1-1.5% depending on your level of income:
http://www.privatehealth.gov.au/healthinsurance/incentivessurcharges/mls.htmLets say that you earn $90k a year. 1% of $90k is $900. This is how much you would pay to the tax man if you don't have private health insurance. This also means, if you can find private health insurance that costs less than $900 a year, you will save money. The cheapest fund for me (I'm in Victoria) is HIF Gold Vital, which is $51 a month (after government rebates), or $612 annually. This means you would save 900 - 612 = $288 a year by having private health insurance. If you are over 31, and don't have private health insurance, you might also be liable for the lifetime loading fees, which will also factor in:
http://www.privatehealth.gov.au/healthinsurance/incentivessurcharges/lifetimehealthcover.htmAnd one other thing - Don't use iSelect or similar commercial websites to find your private health insurance. Use the government site instead - they don't take kickbacks from providers, and will give you more impartial results:
http://www.privatehealth.gov.au/dynamic/compare.aspxIf you earn under $90k a year, there is no cost saving in taking out private health insurance.