Taxing wealth held in private businesses poses two key challenges. First, they must be valued. This is not always straightforward particularly for businesses without an observable and consistent profit stream, and businesses with many intangible assets. Second, not all businesses generate sufficient income to fund wealth tax payments. This paper provides quantitative evidence on the empirical magnitude of these problems, documenting how many and which businesses could be challenging to value, and which business owners could face liquidity constraints. I then zoom in on farm businesses, a particular source of concern for some who worry that farming incomes are low relative to the value of land. I find that a minority of private businesses will be hard to value, and some businesses (including some farms) will face liquidity constraints. However, these problems are not widescale enough to be insurmountable.