My U.S. F1 Visa expires on 30th June 2015, and I am visiting India near end of December this year. Can I apply for F1 visa renewal (category,university, etc. everything remains the same). Is it too early to apply before the expiry of the current visa? Can the US embassy reject the renewal, which may cause problems later on?
According to the official FAQ on non-immigrant visas: Yes, one can apply early to renew, and yes it can be rejected inasmuch as it will be a new application. Below is the quote of the relevant part of the afore-mentioned page:
Q: I have a nonimmigrant visa that will expire soon and I would like to renew it. Do I need go through the whole visa application process again?
A: Yes, you will have to go through the whole visa application process each time you want to apply for a visa, even if your visa is still valid. There are some situations where a visa applicant may not need to be interviewed when renewing his/her visa. See the U.S. Embassy or Consulate website for more information.
Disclaimer: I am not an expert, I simply googled the information.