[bluetech]

The book Radical Markets proposes the following tax (to replace most other taxes), quote:

Every citizen and especially corporation would self-assess the value of assets they possess, pay a roughly 7% tax on these values and be required to sell the assets to anyone willing to purchase them at this self-assessed price.

[RestlessMind]

This is a horrible proposal. Do I have to put a price on my family's home? And if I price it just right, be forced to sell to some speculator who wants it just because he has more money than I do?

[madsbuch]

Another way to think about it is, that you adjust the price continuously. If a speculator offers you money, you are in the position to take the offer or raise your own valuation and pay the increased tax. At some point a sensible person would be like: screw this, I am moving out of the city because the offers are so high, resulting in very high taxes, which is the intended effect.

[cutemonster]

Maybe can work for some types of assets one doesn't use, like parked domains

In your example, you could also say "I have to put a price on our cat, and...?" Or your glasses, or your jeans and underpants. But the proposal probably didn't have such things in mind

[bluetech]

Basically, their answer is yes.

First, under this system, long-term speculation is not really viable, due to the high tax. So the buyer must have some reason for paying higher than the price you set, which you don't see, i.e. you under-utilize the asset. Google/Facebook ads work this way - every slot is always up for auction. Also similar dynamics in partnership agreement's "shotgun clauses", etc.

Second, you can always factor in your sentimentality into your price, then the buyer will buy your neighbor's house instead. But you have to pay for it in the form of a higher tax. This is like a penalty for obstructing economic efficiency.

Third, this system pretty much does away with the strict idea of private property, into what they call "partial common ownership". It's basically a way to have shared ownership (as in communism) without the central planning, i.e. in a way that might actually work. (In fact, it quite reduces the role of government.)

I'm not advocating for this system, but I think it's fun to think about.