Definition of 'Non-Assessable Stock'
A class of stock in which the issuing company is not allowed to impose levies on its shareholders for additional funds for further investment. Non-assessable stocks typically have the words "fully paid and non-assessable" printed on the stock certificate.
These are the opposite of assessable stocks.
Investopedia explains 'Non-Assessable Stock'
Assessable stocks proved unpopular, and most companies switched over to issuing non-assessable stock in the early 1900s . Although equity was no longer sold at a discount compared to its share price, investors were more confident about buying non-assessable stocks because they no longer had to worry about the possibility that the issuer would force them to make more investments after the initial transaction.