Generally, both the purchaser and seller must file Form 8594 and attach it to their income tax returns (Forms 1040, 1041,. Form 8594 is a tax document required in certain business sales where the buyer acquires assets rather than stock or equity.Who Must File Form 8594? Both the seller and purchaser of a group of assets that make up a trade or business need to file Form 8594. Learn how to file form 8594 and when to file. Both the purchaser and the seller must attach Form 8594 to their respective tax returns in the first year of the sale.