An S corporation can own an interest in another business entity. It can also be a partner in a partnership or a member of a limited liability company (LLC). An S corporation can own 80 percent or more of the stock of a C corporation, which can elect to join in the filing of a consolidated return with its affiliated C corporations. However, an S corporation is ineligible to be a member of the affiliated group and to join in the election to file a consolidated return.

The primary mechanism for ownership of another entity is for an S corporation to own a subsidiary S corporation, known as a qualified Subchapter S subsidiary. The subsidiary must be otherwise eligible to be an S corporation if the parent’s shareholders directly owned the subsidiary’s stock. The parent S corporation must own the subsidiary’s stock directly and must own 100 percent of the subsidiary’s stock.

Finally, the parent must elect, on Form 8869, to treat the corporation as a qualified Subchapter S subsidiary. The election of qualified S corporation subsidiary status results in a deemed liquidation of the subsidiary into the parent. If the election later is revoked or terminates, the former subsidiary is treated as a new corporation that acquired all of its assets and assumed all of its liabilities immediately before the termination.

For tax purposes, the separate existence of the subsidiary is ignored. All the assets, liabilities and items of income, deduction or credit of the subsidiary are treated as belonging to the parent S corporation. However, the subsidiary is treated as a separate entity for employment tax liabilities paid in 2009 or later, and certain excise taxes paid in 2008 or later. If the subsidiary was a separate corporation before joining with the parent, the subsidiary remains liable for any taxes that arose during the period when it was separate.