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. Seller and Buyer shall each file, with its respective federal income tax return for the year in which the Closing occurs, IRS Form 8594, and Buyer agrees to. A taxable asset purchase allows the buyer to "step up," or increase, the tax basis of the acquired assets to reflect the purchase price. Please feel free to state your question.