You haven't mentioned the State NEET Counseling you are enquiring about. But going by your profile, we understand that you are enquiring about Maharashtra NEET Counselling. If you do not fill the Status retention form, the seat will not be retained and then you get to participate in the Mop Up Round. The Information Brochure isnt clear about the Mop Up Round seat filling procedure. But if you look at this paragraph: "A candidate who is selected in first or subsequent round of selection process but does not join the college or cancels the admission after joining, it will be presumed that such a candidate is not interested in the admission process and for all further CAP round(s) including MOPUP round(s) of admission. Such candidate shall not be considered for allotment of any seat during NEET UG 2020 admission process thorugh CAP round. " You need to take up that seat allotted in the Mop up round mandatorily. You cannot skip that seat because the Mop Up Round is the last round in the Counselling process.