How can it be not necessary Kritrimpraani !!!! If you do not file for change of status, your wife would be out of status. You need to be smart and alert to avoid these situations. You need to file I-539 -Application To Extend/Change Nonimmigrant Status for your wife. Go to USCIS.gov and download the form with instructions. The fee is $200.00. You have to mail it to the Vermont center I believe. If you need more help, you can always count on me.