When referring to the “cost” of Obamacare, the fair thing to do is cite the $2 trillion figure — and no, that isn’t just because it’s a higher number. The gross figure represents how much the federal government will have to spend on expanding coverage through Obamacare, at least according to the CBO. If the government weren’t spending $2 trillion on insurance coverage, that’s money that could be going to reducing the deficit, spending more on infrastructure or a host of other theoretical policies.

It’s also important to remember that the “gross cost of coverage provisions” estimate was the most-widely cited number back when the comparable figure was $938 billion at the time of the law’s passage. That was the number used by the New York Times, Time, the Associated Press, USA Today and, yes, Vox editor Ezra Klein. It also was in line with Obama’s previous pledge that the law would cost “around $900 billion.” The CBO figure for net cost at the time — $788 billion — was barely referenced in discussions of the legislation.

While on the subject, it’s worth clarifying that the main reason why the gross cost headline number has ballooned from $938 billion to $2 trillion is that each estimate is looking at a different time period. The original estimate was for the years 2010 through 2019, but that understated the true cost, because the major spending provisions didn’t go into effect until 2014.