Transferring from MS to PhD in usa I will be starting my MS in CS in spring 2017. At the time of admission, I was not sure of PhD and hence applied only for MS program. However, I would want to transfer to PhD program. Is it possible to transfer/convert the MS program to PhD? I am start my studies after a gap more than 6 yrs and don't want to wait another semester. 
Since I am an engineering undergraduate, I am eligible to apply PhD without MS program.
It depends on the university.  At mine you have to submit a "Letter of Intent" to the graduate office stating that you wish to continue on to another graduate degree in the university without having to file a formal application. I would talk to the department about how this process works, and your school's graduate office for more information - they may require another formal application, they may not.