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. 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. 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. Caution: If there is an amount on either line 43 or line 44, you must file Form 4720. 4-Year Averaging Period Under Section 501(h).