You should go to the marketplace to update your information by December 15, the last day of open enrollment. The federal and most state marketplaces are not able to automatically re-enroll all enrollees. For example, if you did not authorize the marketplace to access your tax information in order to assess your eligibility for subsidies, you will have to return to update your information. The marketplace will ask you to project your income and household size and select a plan. You need to complete both steps in order to ensure you receive the correct amount of subsidy.
Additionally, if your most recent federal tax filing shows that your income is more than 500 percent of the federal poverty level, you likely received a notice that, unless you return to the marketplace to actively re-enroll, you will be re-enrolled into coverage without any financial assistance. If your projected income is between 100-400 percent of the federal poverty level, you will likely be eligible for subsidies and should return to the marketplace to ensure they have the most accurate, up-to-date information so you can receive subsidies.
The marketplace will also not automatically re-enroll enrollees with financial assistance if enrollees who received advanced premium tax credits in previous years failed to file their taxes for the years they received tax credits. Also, the marketplace will discontinue premium tax credits and cost-sharing reductions for enrollees receiving premium tax credits and cost-sharing reductions who have not contacted the marketplace to update their information for the last two years and no IRS income information available for them. (45 C.F.R. § 155.335; CMS, Guidance on Reenrollments and Redetermination for Exchange Coverage for 2018, July 13, 2017; CMS, Guidance on Reenrollments and Redetermination for Exchange Coverage for 2019 and Later Years).