Feasibility is a valid concern. Here's what I think.
Stocks are traded on public exchanges. Land and buildings stay in one place. Private jets need to land at airports and they each have a tail number. Most things to be sold efficiently are sold in public marketplaces. There are probably some assets that are hard to track, just like there is currently income that is hard to track. Some people are paid in cash and don't report it. A whole multi-billion-dollar black market of drugs, prostitution, etc. exists that is largely not income taxed. It happens. But in general income tax works, and a wealth tax would too.
Actually it is much harder to tax income than wealth hence why there is so much tax avoidance. The simplest way is tax the asset directly and let who ever owns it pay the tax. The block of land is taxed, the bank account is taxed, the bond is taxed, the factory is taxed, the truck is taxed, the cow is taxed, the patent is taxed, the copyright on a movie is taxed, etc, etc.
If you did this you would not need a very high tax rate (my guess is something around 1%) and it would encourage efficient allocation of assets. Of course the owners of all these assets won’t be happy and since they are very powerful this idea has zero chance of ever being adopted.
I actually /really/ like this idea. It also implies that anything of such value must be registered and that it only gets taxed that one time.
For the intangible things I would say that an open bidding process every census period would be a good way of judging what the market thinks it's worth. Adjustments might be necessary for changes in the constitution of an asset. (E.G. There's now a building, discovered natural resource, or it's part of a different sized lot unit.) Approximations in resource description could be used to round up/down and group together the units in an area for some anonymity and consistency.
To prevent collusion in 'sitting' on an area those who own it would also be required to bid in buying it back. If they come out over the median bid then they get their land back (but are taxed at the rate they sold it for), if they don't then they can keep the land but get taxed at the 95th percentile bid rate for that area. The top 1% of bidders would also have the option of buying any asset forfeitures within that area at the price that they listed. That would also be the assessed tax value of that land for that period.
