Updated October 31, 2017
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Open enrollment for health insurance under the Affordable Care Act, a.k.a. Obamacare, begins Nov. 1. Whether you’re one of the roughly 10 million Americans already enrolled, or you’re thinking about enrolling now for the first time, here are three things you need to know:

1The sign-up window is 6 weeks shorter this year

The Obamacare open enrollment period for 2018 coverage runs from Nov. 1 through Dec. 15 for the 39 states that use for individual and family coverage; this is six weeks shorter than last year. Don’t procrastinate: will have to accommodate consumers in a tighter window than last year, and if the web site or call center can’t handle the last-minute volume, you risk missing the deadline. Some states that are running their own exchanges have set their own deadlines. For example, New York State has retained last year’s Jan. 31 deadline. Here is a list of all states that are running their own programs.

2It’s important to shop around

The standard advice applies even more this year. For starters, the shorter open enrollment period means that existing Obamacare consumers who take no action during open enrollment will be automatically re-enrolled after open enrollment ends. If you’re unhappy with your 2018 coverage details or premium but miss the deadline, you won’t get a do-over like you did last year, when you were auto-enrolled for Jan. 1 but could switch plans until Jan. 31.

Secondly, a recent move by the Trump administration to discontinue Obamacare cost-sharing payments has changed this year’s math. Premiums for silver plans will rise an average of 34% this year, according to consulting firm Avalere. That’s bad news if you’re among the 15% of consumers who make too much to qualify for premium subsidies. But it could be good news if you do qualify, since premium assistance has grown to match the rising benchmark silver price. More consumers than in previous years will find that their subsidy covers the entire cost of a bronze plan, leaving them with $0 in monthly premiums, according to an analysis by the Wall Street Journal. What’s more, consumers living in certain places could find a gold plan that costs less in monthly premiums than a silver plan with higher deductibles, according to a New York Times analysis.

3No health insurance? You can still get penalized

Despite numerous Republican efforts this year to repeal and replace it, the ACA is still the law of the land. And that means you’ll still owe a penalty at tax time if you don’t sign up for health coverage, with some exceptions.

Here, the Internal Revenue Service explains the different types of exemptions you might qualify for and how to file for one.