If you wish to permanently withdraw from your course, or temporarily withdraw until such time as you are ready to resume your studies and/or you submit your thesis, you need to let the University know as soon as possible.
Application guidance and further information, including the consequences of withdrawing, can be found on the Cambridge Students websites:
Withdrawal from Study
Withdrawal from Study takes several forms. You may apply for temporary withdrawal before your submission deadline if you wish to take up full-time paid employment. More commonly, you may be withdrawn if you have not met your deadline for submission of your thesis (you will not be withdrawn if you have applied for an extension and your application is still under consideration).
You can also withdraw from your course completely and leave Cambridge. We recommend you speak to your supervisor, College Tutor and/or Department Postgraduate Office before making the decision to permanently leave your course. There may be other options open to you such as intermission or changing down to another degree for an earlier exit.
In addition, you may be removed from the University if you have not made satisfactory progress or paid your fees.
If you are temporarily withdrawn, the University Information Services (UIS) will email giving four weeks' notice before your email address is deactivated. It will allow you to opt to retain the account for a further two months. Also, a department can apply directly to the UCS for a student's email address to remain active for longer periods of time: service-desk@ucs.cam.ac.uk
Reinstatement
Please be aware that temporarily withdrawing from study does NOT stop the clock on your PhD, so if you have not submitted by your thesis by your submission deadline you will be recorded as having overrun.
If you are granted permission to be reinstated and you have already completed the minimum number of terms of research required for your degree, you will be reinstated for submission of your thesis and examination only. You should give an expected submission date on your reinstatement application. If you do not submit your thesis within one month of this date your reinstatement approval will normally be revoked. You would then need to make a fresh application for reinstatement when your thesis is complete.
Only if you have not completed the minimum number of research terms will you be allowed to return to study in Cambridge for the remaining period before submitting your thesis.
If you have not successfully completed a first year registration review before leaving, the Degree Committee may require you to reapply for admission in direct competition with other applicants.