OPT/CPT

Optional Practical Training (OPT) for F-1 Students

Optional Practical Training (OPT) is temporary employment that is directly related to an F-1 student’s major area of study. Eligible students can apply to receive up to 12 months of OPT employment authorization before completing their academic studies (pre-completion) and/or after completing their academic studies (post-completion). However, all periods of pre-completion OPT will be deducted from the available period of post-completion OPT.

STEM OPT Extension

Students who have earned degrees in certain science, technology, engineering and math (STEM) fields may apply for a 24-month extension of their post-completion OPT employment authorization if they:
Are an F-1 student who received a science, technology, engineering, or mathematics (STEM) degree included on the STEM Designated Degree Program List (PDF),
Are employed by an employer enrolled in E-Verify, and
Received an initial grant of post-completion OPT employment authorization based on their STEM degree.

Types of OPT 

All OPT must be directly related to the student’s major area of study. Students may participate in OPT in two different ways:
Pre-completion OPT: F-1 students may apply to participate in pre-completion OPT after they have been enrolled in school for one full academic year. Students who are authorized to participate in pre-completion OPT must work part-time while school is in session. They may work full time when the school is not in session.
Post-completion OPT: F-1 students may apply to participate in post-completion OPT after the completion of their studies. Students authorized for post-completion OPT are allowed to work part-time (at least 20 hours per week) or full-time.
Note: Practical training can be authorized to an F-1 student who has been lawfully enrolled on a full time basis for one full academic year at a college, university, conservatory, or seminary that has been certified by the U.S. Immigration and Customs Enforcement (ICE) Student and Exchange Visitor Program (SEVP) to enroll F-1 students. The one full academic year requirement may be satisfied while in another nonimmigrant category, not just while in F-1 status. Students may participate in OPT both before and after completing their studies. However, all periods of pre-completion OPT will be deducted from the available period of post-completion OPT. 

Applying for OPT

Generally, student who wants to apply for OPT, must:
Request designated school official (DSO) at the academic institution to recommend the OPT. DSO will make the recommendation by endorsing Form I-20 and making the appropriate notation in the Student and Exchange Visitor Information System (SEVIS).
Properly file Form I-765, Application for Employment Authorization with USCIS, accompanied by the required fee and the supporting documentation as described in the form instructions.
Ref : http://uscis.gov

CPT

Curricular Practical Training (CPT) is defined as employment which is an integral part of an established curriculum, including: alternate work/study, internship, cooperative education, or any other type of required internship or practicum which is offered by sponsoring employers through cooperative agreements with the school. Source: [8 CFR 214.2(f)(10)(i)]. CPT is available only prior to the completion of your degree program and you must have a job offer at the time of application. CPT employment may not delay completion of the academic program.

Curricular Practical Training Vs Optional Practical Training

CPT
OPT
CPT is for work before graduation while you're studying
OPT is for work both before and after graduation
Student needs to have a job offer before applying for a CPT
For OPT, it’s not necessary to have a job in hand. However, if a student is unemployed for more than 90 days of the 12 month OPT period, student will lose permission to work and stand to lose F1 status.
CPT is part of the curriculum and related to student’s major or course of study
OPT too has to be related to the course of study.
Course Credit is given for CPT
No Course Credit for OPT
For CPT, students can complete the required documentation and the I-20 form processing which mentions the dates of the approved work period under the CPT. Students can apply for it during your academic year.
For OPT, students can apply for it upto 90 days before the end date of the program and upto 60 days after the end date of the program. Students can choose the beginning date for the OPT period. The day after the program end date is the earliest that the student  may request for. However, they can begin working only after receiving the Employment Authorization Document (EAD). This document contains the start and the end date of the OPT period
In case of CPT, the employer’s name is printed on Form I-20 and students are not authorised to work for someone else. In case of change of employer or multiple employers, student has to go through additional processing and get separate approvals in each case
Under OPT, students are allowed to work for multiple employers, however the employment must be related to the degree course. Students are required to maintain a record of the various jobs taken up with information like job duration, job description and contact information.
Student should apply for CPT at least two weeks before they wish to commence working. It may take around 7-10 working days for the processing through the SEVIS database and completion of the process
For OPT, student should apply to the USCIS and the processing may take upto 90 days.


Ref: http://www.mbacrystalball.com/blog/2016/02/24/cpt-vs-opt-differences/