Now it’s the March deadline that *really* matters.

Today keeps being referred to as Obamacare’s “deadline.” But it’s worth being clear about what kind of deadline it actually is.

Today’s the deadline to sign up for health insurance on HealthCare.gov if you want that insurance to start by January 1st. But that’s it. If you don’t sign up today and instead sign up on Friday, or next Tuesday, your insurance will kick in a bit after January 1st. There’s no difference in premiums. There’s no difference in plans. There are no penalties.

Indeed, today very much isn’t the deadline to sign up for insurance that protects you from the individual mandate. The mandate only kicks in when people have a coverage gap of longer than three consecutive months during the year. That means that buying insurance any time before the end of March is good enough to avoid the penalty.

Tonight’s cutoff mostly matters for people who saw their plans cancelled and want to make sure their replacement coverage begins on Jan. 1 so they don’t have a coverage gap in 2014. For everyone else — and for the law itself — it’s not a very significant deadline.

Of course, if you are not insured in March, you have to pay the penalty/tax/mandate/whatever.