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. Today's goal is to help you understand the importance of IRS Tax Form 8594 in preparing for sale of your business to a third party… Both the buyer and seller must complete IRS Form 8594 during the sale to report the sale and purchase of business assets. – Both the purchaser and seller are required to file Form 8594. – The Form 8594 must be attached to each filer's timely filed Federal income tax return.