The health exchanges are now open, though some have a lot of glitches. You still have lots of questions about how the Affordable Care Act affects you and your family.

And we have answers. In our ongoing series, we're addressing questions you've asked about the sign-up process.

With people having so much trouble logging onto the websites to get coverage, some are wondering how soon they have to sign up for coverage to avoid the potential penalties.

Don't worry, there's still plenty of time. There are really just two important dates to keep in mind. The first is Dec. 15. That's the date by which you need to be signed up if you want your coverage to begin Jan. 1, 2014 — the earliest any of these plans will take effect.

The other date is Feb. 15, 2014. That's the last day you can get coverage and avoid being liable for a penalty for not having insurance. The maximum penalty if you don't have coverage for the entire year is $95 or one percent of your taxable income, whichever is bigger. It will go up in future years.

The open enrollment period actually will run until the end of Mar. 2014, but if you wait until the very end you might still have to pay a month's worth of the penalty for not having coverage. That penalty would be assessed when you pay your 2014 taxes in Apr. 2015.

So people have time to sign up. But the next question is how much insurance will cost and whether subsidies will help pay for it.

Once you get on the website for your state, whether through healthcare.gov or one of the states running their own sites, that's one of the first things you'll be able to find out. You can plug in your estimated annual income for next year and it will give you an idea of how much of a subsidy you may be eligible for. People with incomes between the poverty line and four times that amount will be eligible for help paying their premiums. That's $11,490 to about $45,960 for an individual, and $23,550 to $94,200 for a family of four.

There are also various online calculators you can use, including a subsidy calculator on NPR.org.

Those calculators should also tell you if you might be eligible for Medicaid. Medicaid coverage for those with very low incomes, and is usually free, or nearly free.

Another topic of concern is whether people can sign up for insurance after the current open enrollment period ends. Many listeners have told us that they have coverage from a former employer through COBRA that ends after next March. What happens in that situation?

This is one way that the Affordable Care Act is a lot like the insurance plans most people have at work. Every year there's an open season, and for the most part you can only buy or change plans during that open season. So if next May you haven't bought insurance and you get sick or you just decide you should have gotten insurance and you didn't — then too bad. You'll have to wait until the next open season to sign up.

But there is an exception — and that's if you have one of several life changing events. Moving to another state, getting married or divorced, losing your job-based insurance or having your COBRA coverage end are all things that would allow you to buy insurance on the exchange outside the regular open season. Those events would be handled just as they are in an employment-based health plan.

Finally, there appears to be some confusion as to whether people with health coverage through Medicare need to do anything at all.

The short answer is no, but it's a little confusing. The health insurance exchanges are for people under the age of 65. They're not for seniors who have Medicare, and the exchanges don't sell Medicare prescription drug coverage or supplemental coverage.

Here's where the confusion comes in: Oct. 15 is the start of Medicare's open season. The Medicare open season runs until Dec. 7. During this time, Medicare patients can join or change drug or other health plans. But that's not Obamacare.

So if you're a Medicare patient go to Medicare.gov, Medicare's website. If it warns that it's not completely up to date due to the government shutdown, check back later.

Next month we'll answer more questions about health coverage under the Affordable Care Act. You can send them to [email protected].

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