When an Office action is issued, the applicant has three months to respond to the Examiner with possibility of being extended for an equal period.
If the action is premised on a defect in the mark itself, such as likelihood of confusion, genericness, or descriptiveness, the applicant may need to present evidence and legal argument to overcome this rejection.
In a non-final Office action, the applicant is entitled to reply and request reconsideration or further examination, with or without making an amendment.
If any claim stands allowed, the reply to a final rejection must comply with any requirements or objections as to form.
Note that a shortened statutory period of between one and three months usually applies (justified by the USPTO's desire for speedy prosecution of applications) and responses sent later than the shortened period require the filing of a petition and the payment of a petition fee that varies with the number of additional months requested.
For example, when an Examiner sends a restriction requirement, a one-month shortened statutory period applies, and if the applicant sends a response on the 31st or 32nd day (depending on the month, as well as on Saturday/Sunday/holiday practice; note that February is granted 30 days), a petition for a one-month extension, and the associated fee, must accompany the response.