There are no application deadlines for undergraduate and postbaccalaureate applicants. There are no university application deadlines for graduate applicants either; however, the graduate departments can and do impose application deadlines for their programs. Check with your prospective graduate program for application deadlines.
If you're an international applicant and not currently living in the United States, we strongly encourage you to apply 10-12 weeks before you want to receive your admission decision. If you currently reside in the United States, you should apply 6-8 weeks prior to the date you want to receive your admission decision.