37 CFR § 2.141 - Ex parte appeals.
(a) Appeal from final refusal of application. After final refusal by the trademark examining attorney, an applicant may appeal to the Trademark Trial and Appeal Board, upon payment of the prescribed fee for each class in the application for which an appeal is taken, within the time provided in § 2.142(a)(1). A second refusal on the same grounds may be considered as final by the applicant for the purpose of appeal.
(b) Appeal from expungement or reexamination proceeding. After issuance of a final Office action in an expungement or reexamination proceeding under § 2.93, a registrant may appeal to the Trademark Trial and Appeal Board, upon payment of the prescribed fee for each class in the registration for which the appeal is taken, within the time provided in § 2.142(a)(2).
(c) Appeal fee required. The applicant or registrant must pay an appeal fee for each class for which the appeal is taken. If an appeal fee is not paid for at least one class of goods or services before the expiration of the time for appeal, when the appeal is from a final refusal of an application, the application will be abandoned or, when the appeal is from an expungement or reexamination proceeding, the Office will terminate the proceeding. When a multiple-class application or registration is involved, if an appeal fee is submitted for fewer than all classes, the applicant or registrant must specify the class(es) for which the appeal is taken. If the applicant or registrant timely submits a fee sufficient to pay for an appeal in at least one class, but insufficient to cover all the classes, and the applicant or registrant has not specified the class(es) to which the fee applies, the Board will issue a written notice setting a time limit in which the applicant or registrant may either pay the additional fees or specify the class(es) being appealed. If the applicant or registrant does not submit the required fee or specify the class(es) being appealed within the set time period, the Board will apply the fee(s) to the class(es) in ascending order, beginning with the lowest numbered class.