Yes, leaving your job and losing eligibility for job-based health coverage will trigger a special enrollment opportunity that lasts for 60 days. You can apply for marketplace health plans and (depending on your income) for premium tax credits and cost-sharing reductions during that period. To avoid a gap in coverage between the date your employer plan ends and the start of your marketplace plan, you can enroll in COBRA coverage through your former employer, however, you will need to cancel your COBRA coverage once the marketplace plan takes effect. (45 C.F.R. § 155.420; 79 Fed. Reg. 30240, May 27, 2014).