That's a question asked by the Government Accountability Office, who sent investigators out to test the system.

The results are astonishing.

Washington Post:

In undercover tests of the new federal health insurance marketplace, government investigators have been able to procure health plans and federal subsidies for fake applicants with fictitious documents, according to findings that will be disclosed to lawmakers Wednesday.

The results of the inquiry by the Government Accountability Office are evidence of still-imperfect work by specialists intended to assist new insurance customers as well as government contractors hired to verify that coverage and subsidies are legitimate. The GAO also pointed to flaws that linger in the marketplace’s Web site, HealthCare.gov.

According to testimony to be delivered before a House Ways and Means subcommittee, undercover GAO investigators tried to obtain health plans for a dozen fictitious applicants online or by phone, using invalid or missing Social Security numbers or inaccurate citizenship information.

All but one of the fake applicants ended up getting subsidized coverage — and have kept it. In one instance, an application was denied but then approved on a second try. In six other attempts to sign up fake applicants via in-person assisters, just one assister accurately told an investigator that the applicant’s income was too high for a subsidy.

In their testimony, GAO officials plan to emphasize that the findings are preliminary and that they are continuing the investigation before reaching final conclusions, probably next year. The tests have been done in several states. Because the work is not finished, the GAO is not identifying the states.

[...]

The GAO’s account of fictitious applicants obtaining subsidized coverage goes beyond a related problem that surfaced this spring and that the investigators also cited: The government may be paying incorrect insurance subsidies to a significant share of the 5.4 million Americans who signed up for health plans for this year through the federal marketplace.

The GAO testimony contains updates on that problem, saying that, as of mid-July, about 2.6 million “inconsistencies” existed among applicants who had chosen a health plan and that 650,000 of them had been resolved.

CMS has about 3 months to fix these crater-sized holes in the websites. But officials admit it might not be until sometime next year that the exchanges will be up to snuff. In the meantime, the government will continue to pay out too much - or too litle - in subsidies and fraudsters will continue to be successful in gaming the system.