An equipment bill of sale is a general-use document that records the purchase and sale of any valuable piece of equipment. An equipment bill of sale is a proof of purchase that provides a buyer with evidence that they acquired equipment legally.An equipment bill of sale documents a sale between a buyer and a seller of a certain equipment or tool. Fairfax County, Virginia - Businesses pay tax on furniture and fixtures, machinery and tools, and computer equipment that are located in Fairfax County as of This document releases the seller from any liability and also protects both parties from any disputes that may arise in the future. Proof of Fairfax County residency may be required. Acceptable proof is a driver's license, state ID card, property tax bill or utility bill. Out-of-state dealers file Form ST-8 and collect sales tax based on the rate at the destination of the shipment or delivery (destination-based sales tax). Writing an equipment bill of sale is a crucial legal document for anyone buying or selling large pieces of equipment.