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.The form serves as a record for the IRS, detailing how the purchase price is allocated among various assets to reflect their fair market value. How to File for Purchase Price Allocation. 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. Prepaid expenses and other assets. According to section 1060 of the Internal Revenue Code, the IRS requires that you fill out and file Form 8594 when you're buying or selling a business.