All you would end up doing is creating a new business for accountants to devalue someone’s holdings. I assume that you are saying that the wealth will be the value of the asset less any loan against the property, because that’s the only way a first-time home buyer would be taxed nearly nothing. Why wouldn’t the wealthy simply take loans against their assets thereby devaluing them for the purposes of a wealth calculation? The same way that they borrow against their stock portfolio.