In late 2013, when healthcare.gov was a useless, glitchy mess for members of the public, government officials had another, less-noticed problem on their hands.

Everyone knew — many from experience and many from the news coverage — that the website the government had built to connect Americans with subsidized insurance policies did not work very well on the front end for months after its launch. The dirty secret, though, was that the back-end of the site had not even been built — the part that was supposed to make sure subsidies were set properly and insurers received payments on behalf of each customer.