CNBC Explains

Ticktock: Obamacare deadlines you need to know

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The Affordable Care Act is supposed to help give millions of Americans options for affordable, comprehensive health insurance—but it will be up to those people to take advantage of those options.

The ACA, popularly known as Obamacare, has a number of deadlines that individuals and employers need to keep in mind for years to come to avoid missing out on the insurance options available to them or being financially penalized for failing to comply with the health-care reform law.

Obamacare requires nearly all Americans to have some form of health insurance—either from their employer, Medicare, Medicaid or individually purchased coverage—by 2014 or face a tax penalty, which will grow in amount in future years. Government-run health exchanges, or marketplaces, are being set up in each state to offer insurance coverage to people who lack health insurance or who are looking for more affordable coverage than what they have now.

The first big date in 2013 is Oct. 1, when the health exchanges open for business, and individuals can start comparing premium prices for the insurance plans being offered. The options on state exchanges can be found by going to www.healthcare.gov, which is also where you can learn whether your income qualifies you for government subsidies to offset the cost of insurance.

Oct. 1 is also the start of a six-month open enrollment on the exchanges, the period when people can choose the insurance plan they want and get covered for 2014.

(Read more: Obamacare: CNBC explains)

After that, the deadlines begin. The key ones are:

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Dec. 15, 2013—This is the date you need to enroll for insurance on the exchange and pay your first premium in order for your health coverage to go into effect on Jan. 1, 2014. After Dec. 15, you still can enroll, but your start date for coverage will be delayed by between two and six weeks, depending on what day of the month you enroll.

Jan. 1, 2014—Insurance coverage from plans sold on the health exchanges begin.

Feb. 14, 2014 (or thereabouts)—The date by which most people must sign up and pay for coverage so that it kicks in by the next deadline—March 31—to avoid facing a a tax penalty of $95 for individual adults or 1 percent of their income, whichever is higher. The Valentine's Day deadline is approximate because it can take as much as 15 days to process enrollment applications for coverage to begin the first day of following month.

March 31, 2014—The end of open enrollment on the exchanges. After that, you can only enroll in the exchange's insurance if you have a so-called qualifying life event, such as losing your job, having a child or getting divorced.

Oct. 15, 2014—Open enrollment on the health exchanges for coverage in 2015 begins. In future years, Oct. 15 also will be the opening of enrollment for coverage.

Dec. 7, 2014—Open enrollment for 2015 coverage closes. In future years, Dec. 7 also will be the closing date for enrollment.

Jan. 1, 2015—You must have coverage for the year by this date or pay a penalty of $325 for individual adults or 2 percent of income, whichever is higher.

Jan. 1, 2015—Employers with 50 or more full-time workers must offer affordable, comprehensive insurance by this date or face penalties of $2,000 per employee.

Jan. 1, 2016—Penalty for adults not having health insurance jumps to $695, or 2.5 percent of income, whichever is highest.

Jan. 1, 2018—The so-called Cadillac tax on health plans kicks in. Insurers or self-funded plans must pay a 40 percent excise tax on plans that cost more than $10,200 annually for individuals and $27,500 for families.

—By CNBC's Dan Mangan. Follow him on Twitter at @_DanMangan.