IRS Notice 2014-55 permits a cafeteria plan to allow an employee to revoke their election under the cafeteria plan regarding medical insurance coverage at such time as they are eligible for and elect to enroll in a Marketplace (Exchange) plan

What they did not say in their notice is that someone should carefully consider whether they are getting a better deal by buying coverage with after tax dollars vs. pre tax dollars, and also what the value of any subsidy they may receive would be to offset the difference. Note that the subsidy is NOT available to those that have coverage available through their employer