I quite like the idea of, I think it was @nomadpete's from some time ago about introducing a transaction tax - that is basically every transaction is taxed a percentage..
So, I did something not necessarily statistically valid and haven't yet validated any of it; and I think the idea would have to be refined (e.g. not to price us out of export markets, etc). I asked ChatGPT if we removed all taxes from Australians and replaced it with a flat transaction tax that is not able to be offset like CGT, and the transaction tax is applied at all levels in the Supply Chain, what would be the % required to replace the existing revenues of the government. To ChatGPT's credit, it did also inform me there are many variables and it needed refinement itself, but settled on 10%. I asked it what would be the cumulative impact on consumer prices (so not house transfers, financial investments, loans, etc), to narrow it down. I asked chat as I couldn't be bothered doing the compound math myself, and it said for a 3 stage supply chain process, 33%; 4 stage 47% an d 5 stage 63%. Ouch, but that is a raw value and it doesn't take into account some reduced costs on the way, but businesses would probably take these into profit for a time before competition started to take effect - as per the Whitlam years when he removed a lot of import duties. Also, note, you take roughly 10% off for CGT from those (not entirely accurate but for these purposes will do), as well as for some products (e.g. wine) the baked in taxes that are already there.
Next I asked what would be the impact on net disposable income in quartiles from the lowest income earners (minimum wage) to the highest reported income earner. As expected, this would be regressive, but not by as much as I thought, with the lowest quartile being between 5% and 10% worse off, the next being between 3% and 4% worse off the third being between 3% a 12% better off and the top 25% of earners being between 15% and 55% better off. I didn't go into comparing to how much disposable income each quartile has against some average cost of living for a comparison as that was not the purpose of the exercise. And note, this does not include state and council stand alone revenue and I have not validated how Chat came to its answers.
But it leaves some food for thought for a complete tax overhaul along these lines. The obvious risk is an increase in black market activity to circumvent the taxes. Leaving that aside, I asked Chat what non deductible tax to apply on a proportional basis to the 3rd and 4th quartile to allow the government to distribute income to the 1st and second quartile to ensure that the bottom two quartiles can be directly distributed the money such that they will be no worse off - i.e. net disposable income is the same as the current process. It was 0.55% for the third quartile and up to 2.0% on the 4th quartile. Of course, there will be lots of statistical error in these numbers, but it gives a guide that for no other than a consumption tax, the bottom two quartiles cost of living will not change, yet the top tier will be better off and with a much smaller PAYG tax rate. Of course, it leaves room to move a little more income to those on lower income and according to Chat, around 4.5% applied to both tiers would make the bottom two tiers 10% better off than they were. This would leave the third tier up to 7.5% better off and the top tier up to 49% better off.. and the government still gets the same money. It would probably be in large corporate taxation. They would now have to pay the tax where a lot don't pay anywhere near where they should be.
And then you can factor in additional taxes that we should be charging like the fossil fuel export royalties to the correct level, and you have a far more fairer, flexible, and targetable taxation system.
Of course, this is rudimentary modelling.. There are second and third order factors that have to be addressed. For example, the cost of compliance (accounting, legal, etc) will drop massively as there aren't complex accounting rules required for taxation. This will result is a lower level of transactions and therefore, tax. It may result in increased unemployment as you need less para finance and para legals as well as less tax compliance people in ATO, and if we went federal for all funding (local and state), less public servants at that level collecting, keeping track of, etc. Also, less transactions to billing providers, software, etc. Which can increase government costs (welfare) and reduce taxation, which can increase the transaction tax required, or increase other taxes such as fossil fuel royalties, etc.
But,if we are looking at fairer taxation, then surely the whole system needs reform.
(Sorry for the long post.. first day off for ages.. and I am in a boring meeting).