A Combined Declaration of Use and Incontestability of Trademark (also known as a Section 15 and Section 8 Declaration) is a document filed with the United States Patent and Trademark Office (USPTO) that provides evidence of proper use of a trademark and establishes the right of a trademark owner to sue for infringement of the trademark. It consists of two parts: a Section 15 Declaration of Use and Section 8 Declaration of Incontestability. The Section 15 Declaration of Use is a sworn statement that the trademark is currently being used in commerce and provides evidence of use by submitting specimens of the trademark in use. The specimens should include the trademark on the product or service, the packaging, and any marketing materials. The Section 8 Declaration of Incontestability is a sworn statement that the trademark has been used for five consecutive years without any challenges to its validity. This declaration strengthens the trademark owner’s rights by providing a legal presumption that the trademark is valid and that the registered owner is the legitimate owner of the trademark. The Combined Declaration of Use and Incontestability of Trademark is an important step in protecting a trademark and establishing the owner’s rights to sue for infringement. It can be filed anytime after five years of use of the trademark, but should be filed within one year of the fifth anniversary of use in order to receive the benefits of incontestability.