You can file through a self-developed software or through an AES Certified Service Center or Software Vendor. If you choose one of these filing methods, you must first complete a Letter of Intent (LOI) on the CBP Web site. You can also authorize an agent such as your freight forwarder or air courier to file an EEI on your behalf. You do not need to register or submit an LOI if you authorize your agent to file on your behalf; but you must provide them with the proper written authorization to file on your behalf.