| 2222 | Imagesetting services, pre-press | |
| 5139 | Imitation stones and pearls, jewellery, wholesale | |
| 1600 | Imitation tobacco cigarettes, manufacturing | |
| 2930 | Immersion heaters for water, electric, manufacturing | |
| 2930 | Immersion heaters, household, electric, manufacturing | |
| 7521 | Immigrant admissions, adjudicating, federal | |
| 7521 | Immigrant recruitment, federal | |
| 7521 | Immigrant selection, federal | |
| 7411 | Immigration consultant | |
| 7521 | Immigration services, federal | |
| 7512 | Immunization program administration, government | |
| 3312 | Immunology instruments, manufacturing | |
| 2922 | Impact wrenches, hand held power-driven, manufacturing | |
| 3312 | Impedance measuring equipment, manufacturing | |
| 3312 | Impeller and counter driven flow meters, manufacturing | |
| 3311 | Implants, surgical, manufacturing | |
| 5150 | Implements, farm, wholesale | |
| 7421 | Import and export trade consulting services | |
| 5122 | Importers of wines and spirits for embassies | |
| 5190 | Importers, not otherwise reported | |
| 5121 | Importers, raw wool, wholesale | |
| 5131 | Importers, woollen and worsted goods, wholesale | |
| 5121 | Importing show horses | |
| 1120 | Impounding and storing salt water in connection with petroleum production | |
| 1729 | Impregnating and coating of fabrics | |
| 2423 | Impression material, dental, manufacturing | |
| 3312 | In-built thermostats, filled system and bimetal types, manufacturing | |
| 3150 | Incandescent filament lamp bulbs, complete, manufacturing | |
| 3150 | Incandescent lighting fixtures, manufacturing | |
| 1729 | Incandescent mantles, manufacturing | |
| 2429 | Incense, manufacturing | |
| 3312 | Incinerator control systems, residential and commercial types, manufacturing | |
| 4530 | Incinerator installation, small, contractors | |
| 9000 | Incinerator operation | |
| 9000 | Incinerator operation, hazardous waste | |
| 9000 | Incinerator operation, solid waste | |
| 4520 | Incinerators, industrial construction | |
| 2914 | Incinerators, industrial process type, manufacturing | |
| 2695 | Incinerators, precast concrete, manufacturing | |
| 7530 | Income security programs, federal administration | |