CPT vs OPT Explained — US Internships for International Students on F-1 Visa

Every F-1 student in the US eventually asks the same two questions: can I do an internship during my degree, and can I work after I graduate? The answers are yes to both — but the rules are different, the timelines matter, and one mistake (using too much full-time CPT) can eliminate your post-graduation work rights entirely.

FreeStudentTools breaks down CPT and OPT side by side — what each is, how to apply, what the 12-month cap actually means, and the STEM OPT extension that turns 12 months into 36. If you're an international student on an F-1 visa planning work experience in the US, this is what you need to understand before you sign an offer letter.

What's the Difference Between CPT and OPT?

CPT — Curricular Practical Training

CPT is off-campus work authorisation that lets you do internships, co-ops, or externships during your degree. The critical requirement: the work must be an integral part of your academic programme — meaning it's either required for your degree, earns academic credit, or is tied to a specific course.

How do you apply for CPT?

1. Find an internship or co-op that is directly related to your field of study
2. Get a written job offer letter from the employer stating position title, start/end dates, hours per week, and location
3. Contact your DSO (Designated School Official) at the International Student Office with the offer letter
4. Your DSO may require you to register for an internship course or academic credit to satisfy the "curricular" requirement — some schools offer 0-credit options, others charge tuition
5. Your DSO issues a new I-20 with CPT authorisation, listing the specific employer and dates
6. You can start on the CPT start date in your I-20 — not before

The 12-month full-time CPT cap — the most important rule

If you use 12 or more months of full-time CPT (20+ hours per week), you lose all OPT eligibility. Permanently. This is the single most consequential rule in the CPT/OPT system, and many students don't learn about it until it's too late.

Part-time CPT (under 20 hours per week) doesn't count toward this cap regardless of how long you use it. A student who does part-time CPT for 3 years still has full OPT eligibility. A student who does full-time CPT for 12 months has zero OPT remaining.

Co-op programmes — which are typically alternating semesters of full-time study and full-time work — can hit this cap before graduation if the student doesn't track carefully. Talk to your DSO before accepting a co-op offer.

OPT — Optional Practical Training

OPT gives F-1 students 12 months of work authorisation to gain practical experience related to their field. Most students use it after graduation (post-completion OPT), though you can use a portion before graduation (pre-completion OPT), which counts against your 12 months.

Post-completion OPT — the typical path

• Authorises up to 12 months of full-time work after graduation
• You can work for any employer in your field — you're not tied to a specific company
• You can change employers during OPT — no new approval needed
• The OPT period starts on the date on your EAD card, not when you start working
• If you're unemployed for more than 90 days total during OPT, you fall out of status

How to apply for post-completion OPT

1. Apply to your DSO at least 90 days before your desired start date (up to 90 days before graduation)
2. Your DSO recommends OPT on your SEVIS record and issues a new I-20
3. File Form I-765 (Application for Employment Authorization) with USCIS — online or by mail
4. Pay the $410 filing fee
5. USCIS processes in 3–5 months and mails your EAD card
6. You can start working on the EAD start date — not before it arrives

What Is the STEM OPT Extension?

If you graduated from a STEM (Science, Technology, Engineering, Mathematics) programme on the DHS STEM Designated Degree Programme List, you can apply for a 24-month STEM OPT extension. This extends your post-graduation work authorisation from 12 to 36 months total.

STEM OPT requirements

• Your degree must be in a STEM-designated field (check the official DHS list — it's updated periodically)
• Your employer must be enrolled in E-Verify (the federal employment eligibility system)
• You and your employer must complete a Training Plan (Form I-983) outlining your learning objectives and how the work relates to your STEM degree
• You must apply for STEM OPT before your standard OPT expires — apply at least 90 days before the OPT end date
• The STEM OPT extension approval is free (no USCIS filing fee)

STEM OPT is the most significant benefit available to F-1 STEM graduates. The extra 24 months significantly improves your chances of receiving an H-1B visa (the main work visa after OPT), since the H-1B lottery runs once per year and many applicants need multiple attempts. Our guide to OPT and STEM OPT for F-1 students covers the full application process in detail.

What Are the Most Costly CPT and OPT Mistakes?

1. Starting work before CPT is authorised — a single day of unauthorised employment is a status violation
2. Accumulating 12 months of full-time CPT — permanently eliminates OPT eligibility
3. Applying for OPT too late — USCIS takes 3–5 months; late applicants work unpaid waiting for their EAD
4. Exceeding 90 days of unemployment during OPT — triggers status violation; track days off between jobs carefully
5. Working for an employer not enrolled in E-Verify on STEM OPT — your employer's E-Verify status is your responsibility to verify before starting

The bottom line

CPT lets you build work experience during your degree, for free and quickly — but use full-time CPT carefully to protect your OPT. OPT gives you 12 months after graduation to work in any related role, expandable to 36 months if you're a STEM graduate with an E-Verify-enrolled employer.

Both programmes are genuinely valuable career tools — US employers are familiar with them and the process is manageable. Start the OPT application 90 days early, track your CPT hours to avoid the 12-month trap, and work closely with your DSO throughout.