That just sounds like an estate tax with a 100% bracket. If the issue is that the super-rich create and abuse loopholes, eliminate the loopholes; that's a different problem from the basic structure of the tax. Admittedly it's a fucking huge problem and there is an argument to be had that it's easier to just burn the whole thing down and build from scratch.
No, the core of my argument is the assumption that the government uses tax revenue. As long as revenue is to be raised there is a debate to be had over what ways are better or worse to raise that revenue by. And what standards we should use to judge better and worse. Where the money is spent is a different issue entirely.
Well, no. This is a very different purposal than a 100% bracket. 100% bracket means you should earn $12 million in wealth, or whatever, and stop. This still lets you accumulate wealth and give it to who you want, it just forces you to break up a fortune, but in a controlled way that makes sense to the people involved.
If your focus is on revenue raising, and not equity, then the Estate tax is, well, a terrible way to do it: it raises about
$20 billion in income as of 2015. In a budget of $3,000 billion, and given all the compliance and enforcement costs of complying with it, the link above suggests the Estate tax reduces overall GDP by about 1%, so in order to raise $20 billion were by that estimate suppressing the economy by $200 billion dollars to raise $20 billion in revenue.
The estate tax as far as I can tell simply isn't justifiable as a revenue raising mechanism: it doesn't gain a bunch of money, and inflicts a lot of deadweight losses in driving people into suboptimal activities like structuring trusts, paying a lot of money to lawyers, and how expensive and difficult actually figuring out the true value of an estate actually is.
Therefore, an estate take has to be justified on non-revenue raising goals: a 1% reduction in GDP might be a worthwhile cost if excess concentrations of wealth are destabilizing to a country, so sacrificing 1% GDP now buys a more harmonious, efficient, and whatever else a less unequal society may allow. But, if were implementing it for other social goals besides revenue generation for the government, which it is terrible for, then we have to contend with the fact that it, well, is self evidently terrible at reducing wealth inequality, given how wealth inequality has by all those measurements increased despite the estate tax, and there are more effective schemes to achieve those goals, if we even agree that is a goal worth persuing, like what I outlined above.