My wife came to US on H4 visa in April 2011, with visa valid until April 2014. In Aug 2011 she started full time Masters program at University. We want to change her status to F1 visa from H4 so that at the end of program she can use OPT. she is also planning to travel to my home country in May after end of her second semester. we want to file change of status from H4 to F1 in June after she comes back to US in June. I want to know if the 30/60/90 day rule applies in her case or not? If we file for COS immediately after coming back in June 2012 will it cause any issue due to this rule as we are filing within 30 days of her re-entry on H4? we want to apply for COS in June because, there is possibility of her getting assistantship in Fall, which she cannot accept if she is on H4 visa.