Of the counter-productive effects? I have a bunch of shares in a private company that I was given for good performance and retention. At the latest share price from the latest funding round they’re worth more than enough to put me in the 0.5%. However, they’re not liquid - I can’t sell them unless the company floats or is bought. Under a simple wealth tax I’d have to pay many thousands of pounds of tax on them every year despite them having no realisable value. Just because something is an asset with a nominal value doesn’t mean it’s liquid or generating income. Obviously when (if) I sell the shares I’ll pay capital gains, or if they generate a dividend, income tax.