1109.15 Filing Fees 
Payment of the filing fee for at least a single class is a minimum filing requirement. See 37 C.F.R. §§2.88(b)(3), (e)(i); In re L.R. Sport Inc., 25 USPQ2d 1533 (Comm’r Pats. 1992).
In a multiple-class application, if the applicant files a statement of use electronically, TEAS will require payment of the fees for all classes. However, if the applicant files a statement of use for a multiple-class application on paper and includes the fee for only one class of goods/services, the ITU staff will issue an Office action granting the applicant 30 days in which to submit the missing fees to cover allclasses or specify the class(es) to be abandoned. The additional fees may be paid after the time for filing the statement of use has expired, within the period for response to the Office action. If the applicant does not submit the fees or specify the classes to be abandoned within the set time period, the USPTO will apply the fees paid to the lowest-numbered class(es) in ascending order, and will delete the goods/services in the higher-numbered class(es) from the application. 37 C.F.R. §2.88(b)(3).
If an applicant files a statement of use and a request to divide the application at the same time, and the fees submitted are sufficient for one but not both, the fees will be applied first to the statement of use, and the applicant will be notified of the deficiency. See TMEP §§1110.02 and 1110.07 for further information about filing fees for requests to divide.
If the applicant files an "insurance" extension request in conjunction with a statement of use ( see TMEP §1108.03), and the applicant submits fees sufficient for one but not both, the USPTO will apply the fees as follows: (1) if there is enough money to cover the extension request, the USPTO will apply the fees to the extension request to avoid abandonment of the application; or (2) if there is enough money to cover the statement of use, but not enough to cover the extension request, the USPTO will apply the fees to the statement of use.
See TMEP §1109.15(a) regarding returned checks, EFT and credit card payments that are refused by financial institutions, and fees charged to deposit accounts with insufficient funds.
1109.15(a) Processing Deficient Fees
If the filing fee for at least a single class is deficient (e.g., if the fee is charged to a deposit account with insufficient funds, an EFT or credit card payment is refused or charged back by a financial institution, or a check is returned unpaid), the fee for at least one class of goods/services must be repaid before the expiration of the statutory filing period, or the application will be abandoned.
If a check is returned unpaid or an EFT or credit card payment is refused, and the statement of use was accompanied by an authorization to charge deficient fee(s) to a deposit account (37 C.F.R. §2.208) that has sufficient funds to cover the fee, the USPTO will charge the filing fee for the statement of use and the fee for processing the returned check or refused payment (37 C.F.R. §2.6(b)(12) ) to the deposit account.
If the examining attorney determines, before taking an action regarding the statement of use, that the filing fee for at least a single class of goods or services has not been paid, the examining attorney should e-mail the ITU/Divisional Unit and request that the SOU Processing Complete status be withdrawn and that the ITU staff notify the applicant in writing of the defect. See TMEP §1109.15.
If the examining attorney determines, after taking an action regarding the statement of use, that the filing fee for at least a single class of goods or services has not been paid, and there is time remaining in the statutory period for filing the statement of use, the examining attorney will issue an Office action refusing registration on the ground that the filing fee for the statement of use was not paid and will require the applicant to submit the filing fee on or before the statutory deadline. If the fee was not paid because a check was returned unpaid, or an EFT or credit card was refused, the examining attorney will also require submission of the processing fee required by 37 C.F.R. §2.6(b)(12). The processing fee may be paid after expiration of the statutory deadline for filing the statement of use.
If the fee for at least a single class has not been paid, and there is no time remaining in the statutory period for filing the statement of use, the examining attorney will issue an Office action refusing registration and stating that the application is abandoned because a proper statement of use was not filed within the time required by statute. 37 C.F.R. §§2.88(e)(1), (h). In such a case, the examining attorney must issue a regular Office action, with a six-month response clause. If the applicant does not establish within the six-month response period that the fee for at least a single class of goods/services was paid prior to the expiration of the statutory filing period, the application will be abandoned.
If the fee for at least a single class is paid before expiration of the statutory deadline, but the fee(s) for additional class(es) are deficient, the examining attorney will issue an Office action requiring the applicant to submit the missing fees to cover allclass(es) or specify the class(es) to be abandoned. The additional fees may be paid after the time for filing the statement of use has expired, within the six-month period for response to the examining attorney’s Office action. If the applicant does not submit the fees or specify the classes to be abandoned within the set time period, the USPTO will apply the fees paid to the lowest-numbered class(es) in ascending order, and will delete the goods/services in the higher-numbered class(es) from the application. 37 C.F.R. §2.88(b)(3).
If the statement of use has been approved and the mark is registered when the Office learns that the fee for the statement of use was deficient, the USPTO will cancel the registration as inadvertently issued, because the statutory requirements for registration have not been met. If the fee for at least a single class of goods/services was not paid before the expiration of the statutory filing period, the application will be abandoned. If the fee for at least a single class of goods/services was timely paid, but the fees for additional class(es) have not been paid, the USPTO will restore the application to pendency and refer it to the examining attorney for appropriate action.
See TMEP §405.06 regarding payments that are refused.