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. Line 1: Enter the name, address, and Tax Identification Number (TIN) of the other party (either the purchaser or seller). Your preparation and careful tax planning may help determine whether the closing of the sale has significant tax issues. Learn how to file form 8594 and when to file. Both the buyer and seller must complete IRS Form 8594 during the sale to report the sale and purchase of business assets.