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. Learn how to file form 8594 and when to file. 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. The basis in the assets acquired will generally include T's liabilities assumed in the transaction.