The manner in which a parent company structures the spinoff and divests itself of a subsidiary or division determines whether the spinoff is taxable or tax-free. The taxable status of a spinoff is governed by Internal Revenue Code (IRC) Section 355. The majority of spinoffs are tax-free, meeting the Section 355 requirements for tax exemption because the parent company and its shareholders do not recognize taxable capital gains.

While a company's first responsibility in determining how to conduct a spinoff is its own continued financial viability, its secondary legal obligation is to act in the best interests of its shareholders. Since the parent company and its shareholders may be subject to sizable capital gains taxes if the spinoff is considered taxable, the inclination of companies is to structure a spinoff so that it is tax-free.

There are two basic structures, or means, for a parent company to conduct a tax-free spinoff. Both result in the spinoff becoming its own legal entity, a publicly traded company separate from the parent company, although the parent may hold a substantial amount of stock – up to 20% by IRC guidelines - in the newly created company.

The first method of conducting a tax-free spinoff is for the parent company to distribute shares in the new spinoff to existing shareholders in direct proportion to their equity interest in the parent. If a stockholder owns 2% of the shares of the parent company, he receives 2% of the shares of the spinoff company.

The second tax-free spinoff method is for the parent company to offer existing shareholders the option to exchange their shares in the parent company for an equal proportion of shares in the spinoff company. Thus, shareholders have the choice of maintaining their existing stock position in the parent company or exchanging it for an equal stock position in the spinoff company. The shareholders are free to choose whichever company they believe offers the best potential return on investment (ROI) going forward. This second method of creating a tax-free spinoff is sometimes referred to as a split-off to distinguish it from the first method.

A taxable spinoff, with potentially substantial capital gains tax liability for both the parent company and its shareholders, results if the spinoff is done by means of outright sale of the subsidiary company or division of the parent company. Another company or an individual might purchase the subsidiary or division, or it might be sold through an initial public offering (IPO).

There are any number of reasons why a company might wish to spin off a subsidiary company or division, ranging from the idea that the spinoff can be more profitable as a separate entity to the need to divest the company to avoid antitrust issues.

There are detailed requirements in IRC section 355 that go beyond the basic spinoff structure outlined above. Spinoffs can be quite complicated, especially if transfer of debt is involved. Therefore, shareholders may wish to seek legal counsel on the possible tax consequences of a proposed spinoff.