The owner of the denaturing facility would not necessarily be a registered party under the regulations. The company and facility IDs of the importing party who owns the renewable fuel at the time a RIN is generated (based on the volume of renewable fuel with denaturant) are the company and facility IDs that must be included in the RIN. (The owner of the renewable fuel should know the volume of the fuel coming out of the denaturing facility since it owns and will either sell or use the denatured fuel.)
The importing company that owns the fuel would need to register the facility, typically leased tankage, with which it has contracted to store and denature the renewable fuel (i.e., has custody) as one if its own facilities with its own facility ID number. This means that a facility owned by a company that simply leases tankage may never be a registered party but several registered importers may have a separate facility ID for that tankage facility. This scenario would not apply to domestic producers because ethanol intended to be used as motor fuel would be denatured at the facility where it was produced.
Question and Answer was originally posted at: Questions and Answers on the Renewable Fuel Standard Program (PDF) (55 pp, 221 K, EPA420-F-07-041a, August 2007, About PDF)