Listen up, procrastinators: March 31 is now the only date to circle on your Obamacare calendar.

That's the 2014 deadline to apply for coverage and not face tax penalties under an extension announced late Monday by the Obama administration.

The six-week delay resolves two conflicting dates: the open enrollment window extended beyond the deadline to obtain coverage. The extension does not involve people covered under employer health plans or government coverage such as Medicare or Medicaid.

Coverage through the health exchanges begins Jan. 1, but customers don't have to enroll in a plan that quickly. The Affordable Care Act allows individuals to go without coverage for up to three months at a time. It also specifies a mid-month application deadline for coverage to begin the next month.

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The law says the open enrollment window is open through March 31. But if individuals waited until that day to register, their coverage wouldn't begin until May, long after the three-month clock that started Jan. 1 reached zero.

That meant a Feb. 15 application deadline.

The extension removes this confusion.

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Faced with a malfunctioning website and confusion over the deadline, the agency running the insurance marketplace said it would give customers the extra time.

The penalty is known as the "shared responsibility payment." Someone who is required to but does not have health coverage in 2014 would pay it in their taxes due April 15, 2015. It is $95 or 1% of income, whichever is greater, and increases quickly -- to at least $325 for 2015 and $695 for 2016.