Some "charitable" organizations do register with the state in which they reside and even incorporate in that state as nonprofit corporations and never apply for federal tax-exempt status
However, many small "charitable" organizations never seek recognition as a nonprofit from their state or the federal government. The disadvantage to not becoming a registered nonprofit is that donors cannot take a tax deduction on their donations, and you cannot receive grants from foundations or corporations.
Becoming a 501(c)(3) organization is not for the faint of heart. It involves a lot of paperwork and some expense. Think carefully before you begin the arduous process of a becoming a tax-exempt nonprofit organization. If your purpose is simple and/or time limited, you may be able to accomplish your mission without tax-exempt status.
