| 7511 | Income tax collection, federal administration | |
| 7511 | Income tax collection, provincial administration | |
| 7412 | Income tax compilation services | |
| 7412 | Income tax preparation services | |
| 7412 | Income tax return preparation services without accounting, auditing, or bookkeeping services | |
| 3000 | Incoming mail handling equipment (e.g., opening, sorting, scanning), manufacturing | |
| 3311 | Incubators, infant, manufacturing | |
| 3312 | Incubators, laboratory type, manufacturing | |
| 2921 | Incubators, poultry, manufacturing | |
| 2429 | Indelible inks, manufacturing | |
| 7430 | Independent advertising copywriter | |
| 6720 | Independent insurance claims adjusters | |
| 9241 | Independent sports instructors | |
| 6303 | Independent truck driver to road transportation (except owner/operator) | |
| 2109 | Index and other die-cut cards, made from purchased cardboard | |
| 2429 | India inks manufacturing | |
| 7512 | Indian affairs program, federal government | |
| 7511 | Indian band or tribe council | |
| 3693 | Indian clubs, manufacturing | |
| 5150 | Indicating instruments and accessories, wholesale | |
| 3312 | Indicating instruments, electric, manufacturing | |
| 3190 | Indicator panels (metal), manufacturing | |
| 3312 | Indicator testers, turntable, manufacturing | |
| 3313 | Indicators, industrial process control type, manufacturing | |
| 2930 | Indirect water heaters and converters, electric, domestic, manufacturing | |
| 2411 | Indium chloride, manufacturing | |
| 9500 | Individual employing a care-giver | |
| 6599 | Individuals investing in financial contracts on own account | |
| 7430 | Indoor display advertising services | |
| 9212 | Indoor motion picture theatres | |
| 9249 | Indoor play areas | |
| 2914 | Induction heating equipment, industrial process type, manufacturing | |
| 3110 | Induction motors, electric, A.C., manufacturing | |
| 3110 | Inductors, electronic component type (e.g, chokes, coils, transformers), manufacturing | |
| 7010 | Industrial and commercial buildings, operators of | |
| 9111 | Industrial associations | |
| 9301 | Industrial bag cleaning service | |
| 6519 | Industrial banks (i.e., known as), depository | |
| 6592 | Industrial banks (i.e., known as), non-depository | |
| 1729 | Industrial belting reinforcement, cord and fabric, manufacturing | |