A sales agreement for buying a business is necessary for keeping both the parties on the same page and avoiding any legal trouble. The Asset Purchase Agreement Checklist outlines important considerations for buying or selling a business, including assets, liabilities, and contracts.Both the seller and purchaser of a group of assets that makes up a trade or business must use Form 8594 to report such a sale. An asset purchase agreement is a legal document used when buying or selling a small business. Read on to understand the basics. Have the completed Business Certificate form notarized. ASSET PURCHASE AGREEMENT from SPIRE Corp filed with the Securities and Exchange Commission.