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.Line 4: Enter the fair market value for each asset class and specify the portion of the total sales price allocated to that class. Form 8594 is a tax document required in certain business sales where the buyer acquires assets rather than stock or equity. Both the buyer and seller must complete IRS Form 8594 during the sale to report the sale and purchase of business assets. Learn how to file form 8594 and when to file. 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.