When a student completes a suspension, when they're allowed to return to campus and return to attending class is going to depend on several factors. One, it will depend on the particular college or university involved. Two, it will depend on the specific provisions of the sanction itself.
At many schools, if a student is suspended, it's not necessarily an automatic re-admittance to the school. Oftentimes conditions would be imposed in addition to the suspension, such as counseling of some kind, whatever the case may be. Proof of completion of the conditions, for one, would have to be provided to the school in advance. That alone may not be everything that the school requires. At some schools, they also require a student to actually reapply. If a student is suspended, it is a serious matter. Although the general expectation or understanding is that a student can return. It's not necessarily automatic. It can definitely create complications. An experienced attorney-advisor can help navigate the process, and should be involved as early as possible in the process.