Form 8594 must also be filed if the purchaser or seller is amending an original or a previously filed supplemental Form. 8594 because of an increase or decrease.Form 8594 is a tax document required in certain business sales where the buyer acquires assets rather than stock or equity. The tax professional who comes into contact with such a situation should consider the need to file Form 8594, or to revise the valuation of specific assets. Learn how to file form 8594 and when to file.