I never understood the logistics of a wealth tax. Wouldn't that require every single person to document all of their wealth to prove that they are not in the to

I never understood the logistics of a wealth tax. Wouldn't that require every single person to document all of their wealth to prove that they are not in the top bracket and this don't owe anything? If it doesn't what is to stop somebody who is near the borderline from just refusing to document? Won't there also be tons of loopholes to diversify your holdings to keep yourself just below the cutoff?