Yes, leaving your job and losing eligibility for job-based health coverage will trigger a special enrollment period that lasts for 60 days (although there may be an extension for exceptional circumstances). You can apply for marketplace health plans as well as premium tax credits and cost-sharing reductions during that period depending on your income. If you need 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).