You have 60 days to file (in writing by mail, in my case) once you leave your previous job, I didn't have enough time between jobs to really need it, emergency happens + a few weeks of recovery time where I'm incapable of basically doing anything, I get a few bills, I pay them, start working at my new job, get more and much larger bills, now I'm ineligible for Cobra. Not that it would have mattered with that insurer anyway in my case.