Under 15 U.S.C. § 1065, a trademark owner can file a Section 15 declaration for incontestability of their trademark. The declaration states that the trademark has been in use for at least five years after registration. An owner must file a Section 15 declaration within one year of a window in which the owner used the mark for five consecutive years. Typically, the filing occurs between the fifth- and sixth-year post-registration.
An incontestable trademark cannot be subject to a cancellation proceeding based on descriptiveness of the mark. The incontestable status provides a presumption that the mark has acquired secondary meaning. However, incontestable trademarks can still be cancelled if the mark is generic. In addition, abandonment (or non-use) of a mark provides grounds to cancel an incontestable trademark.