This list of principal business activities and their associated codes is designed to classify an enterprise by the type of activity in which it is engaged to facilitate the administration of the Internal Revenue Code. These principal business activity codes are based on the North American Industry Classification System.

Using the list of activities and codes below, determine from which activity the company derives the largest percentage of its “total receipts.” Total receipts is defined as the sum of gross receipts or sales (page 1, line 1a) plus all other income (page 1, lines 4 through 10). If the company purchases raw materials and supplies them to a subcontractor to produce the finished product, but retains title to the product, the company is considered a manufacturer and must use one of the manufacturing codes (311110-339900).

Once the principal business activity is determined, entries must be made on Form 1120, Schedule K, lines 2a, 2b, and 2c, or on Form 1120-A, Part II, lines 1a, 1b, and 1c. For the business activity code number, enter the six digit code selected from the list below. On the next line (Form 1120, Schedule K, line 2b, or Form 1120-A, Part II, line 1b), enter a brief description of the company's business activity. Finally, enter a description of the principal product or service of the company on Form 1120, Schedule K, line 2c, or Form 1120-A, Part II, line 1c.

211110 - Oil & Gas Extraction
212110 - Coal Mining
212200 - Metal Ore Mining
212310 - Stone Mining & Quarrying
212320 - Sand, Gravel, Clay, & Ceramic & Refractory Minerals Mining & Quarrying
212390 - Other Nonmetallic Mineral Mining & Quarrying
213110 - Support Activities for Mining

221100 - Electric Power Generation, Transmission & Distribution
221210 - Natural Gas Distribution
221300 - Water, Sewage & Other Systems
221500 - Combination Gas & Electric

551111 - Offices of Bank Holding Companies
551112 - Offices of Other Holding Companies

611000 - Educational Services (including schools, colleges, & universities)