Assuming you have an updated I-20 from ISSS, for most academic programs the soonest you can begin working under CPT each semester is the day AFTER the end of the current/previous semester for which the CPT is granted. For example, if you have CPT for the next semester, and the current semester ends on the 15th of the month, you can technically begin working on the following day, the 16th if your I-20 shows the 16th as the start date.
CPT for each semester goes until the end of that semester. So, if the semester ends on the 15th of the month, your CPT ends on the 15th of the month. To continue working under CPT beyond the 15th of the month, you will need to go through the reporting/approval/I-20 process again. Remember to allow 3 weeks for the entire process, so start early if your employment continues beyond the end of a single semester. Remember that the position will need to meet the minimum weeks/hours requirements for each semester.
Contact your Internship Advisor if you have questions or want to discuss your situation.
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