I'm not qualified to produce a solution either, but I think changes to taxation in some form are inevitable. One of the big issues with taxation is who gets the money. Income tax and GST is collected by the Federal governement, who portion out some of it to the States. If the States need/want more money they need to rely on things like stamp duty, land tax, and fees, charges & fines. So even when it would be logical to make coordinated changes to income and weath taxes it is not really politically feasible.

My understanding is that, like with income tax, a tiered rate instead of a flat rate would be fairest. So if you put a low (or no) tax on properties under the average price you would only be taxing those with a large amount of accumulated wealth. Combine that with a deferred payment option (think HECS for houses, with the loan secured by the house) and I think you would have a fair system.

When you combine tiered taxes with a flat rate benefits system you get the fairest outcome - and you cut a lot of red tape. Which is a major benefit of a universal basic income. Strip out the means testing all together - give everyone basic income support, a pension once they reach a set age, pay for education, childcare etc. If you are a multi billionaire you are still going to be paying way more in tax than you receive in the pension, if your education leads you to have a higher income you will be paying it back through your increased tax, we don't need HECS. And if you remove all of that time and money that goes into Centrelink compliance bullshit we could probably give everyone a four day working week without noticing the slightest difference in productivity.