lol...who said F1 is invalid once you start working? It is valid for the period of OPT as well. Here is more information available from middlebury website.
http://www.middlebury.edu/NR/rdonlyres/
FC642780-2358-4F59-813D-1B88C5928ED8/0/PostcompletionOPTguidelines.pdf
Post-Completion OPT information
Make copies of both the front and the back of your EAD (Employment Authorization Document) card and the mailer (cardholder). A lost or stolen card cannot be quickly or easily replaced, so copies are essential. A copy of the card will be necessary for future immigration applications
During your OPT period, you remain in F-1 student status under the sponsorship of Middlebury College. To maintain your F-1 status, you must:
• Update your SEVIS record with your new address within 10 days of your move.
• Have your I-20 signed every 6 months.
• Inform ISSS if you will be leaving the country.
• Inform ISSS if your employment comes to an end.
• Inform ISSS if you change to another visa status
You may travel outside of the U.S. before and during your OPT period. However, you should have your EAD card AND AN OFFER OF EMPLOYMENT to re-enter the U.S. in F-1 visa status. Immigration regulations state that if you depart the U.S. while on OPT, you may return to the U.S. to “resume employment after a period of temporary absence†(less than 5 months.) The immigration official at the border may inquire as to whether you are returning to the United States to resume employment. You should be prepared for this question.
If you leave the U.S. and plan to return to work on OPT, you must bring the following documents with you upon entry to the US:
• I-20 signed by International Student and Scholar Services within the last six months
• Valid F-1 visa
• Valid Employment Authorization Document (EAD) card
• Proof of employment (a letter from the company stipulating the terms of your employment). You should show the proof of employment only if asked. The employment letter should only reference OPT employment dates.
If you enter the United States through the Visa Waiver program, as a tourist, or in any other status other than F-1, your OPT will automatically end, even though you have an Employment Authorization Document. You must be in F-1 status in order to have OPT employment authorization. Your I-94 card is proof of your status.
If your F-1 visa has expired, you will need to apply for a new F-1 visa at a U.S. Embassy or Consulate to re-enter the U.S. You may be required to show documentation that you have a job to return to and sufficient income or funds to cover your living expenses. As soon as you receive your passport with the visa stamp from the Consulate, please look at the visa type to ensure that an F-1 visa has been granted. (There have been a few cases over the years where a B-1/B-2 visa was granted in error.) If another visa type has been granted in error, you should inform the Consulate immediately. It is relatively easy to correct the visa type if you do so as soon as you receive the visa. If you leave the Consulate without correcting the visa type, it is extremely difficult, if not impossible, to correct it later.
Travel to Canada, Mexico, or the adjacent islands with an expired F-1 visa: Individuals are able to enter the U.S. using an expired F-1 visa from Canada, Mexico or the adjacent islands, as long as the trip was for 30 days or less, and you did not travel to a third country during that time. This is referred to as “automatic visa re-validationâ€. Citizens of Cuba Iran, North Korea, Libya, Sudan, and Syria. Citizens of these countries are not eligible for automatic visa revalidation, and must have a valid visa to re-enter the U.S.
While on OPT, you are required to file Federal and State income tax forms. The amount of income tax you are liable for depends upon your tax status and upon the tax treaty (if any) that exists between your country of citizenship and the United States.
Post-Completion OPT information
Completion of your OPT period
Once your OPT program is complete, you have three options:
1. Depart from the United States within your 60-day grace period.
You are granted a total of 60 days grace period upon graduation. According to the most strict reading of immigration regulations, any grace period you use between graduation and your OPT start date is counted against the total 60 days grace period. (For example, if you use 50 days between graduation and your OPT start date this would only leave you with a 10 day grace period.)
(I disagree on this one even though they mention "most strict reading of immigration regulations..." From what I know from people I have consulted in the past, you indeed get 60 day grace period after your OPT is over no matter when you started your OPT within the 60-day period after your graduation)
2. Enroll in another U.S. institution as a full-time student.
If you will enroll in F-1 status at your new school, Middlebury College can transfer your SEVIS record to the new school. Please contact your new school to obtain the necessary SEVIS Transfer Form. You are able to remain in the U.S. while a transfer of your SEVIS record is pending, as long as you begin your studies in the next available term, or within 5 months of your OPT end date (whichever is shorter).
3. Change to a different visa status.
This can be done within the United States by applying for a change of status to USCIS, or by departing from the U.S. and re-entering using another type of visa. Please note that if you will remain in the U.S. and apply for a change of status through USCIS, you must apply for a change of status before your OPT end date.
TRAVEL WARNING IF YOU ARE CHANGING YOUR VISA STATUS
If you apply for a change of status from F-1 to another visa category within the United States, you should not travel outside the U.S. without consulting with the person handling your status change. USCIS considers departing from the U.S. while a change of status pending as “abandoning your application.†If you travel outside the U.S. while a status change in pending, you must request “consular processing†of your change of status, and must remain outside the U.S. until your change of status is approved, and then apply at a U.S. Embassy for the necessary visa to enter the U.S. in your new visa category. Again, you should discuss your travel plans with the person handling your change of status.
