The White House is urging insurance customers who enrolled through its online healthcare exchange to check whether they will actually receive coverage amid continuing uncertainty over the effectiveness of the system connecting the website to insurers.

Although officials declared on Sunday that the consumer-facing front end of the federal website was now working effectively for the majority of customers, there have been separate concerns over the back end, which processes applications and passes on financial information to insurers selling the policies.

Speaking on Monday, White House spokesman Jay Carney insisted that many of the underlying causes of the problem had been addressed by weekend software upgrades, but he revealed that the Centers for Medicare & Medicaid Services (CMS), the agency behind the troubled website, had been forced to contact existing users to make sure they did not fall between the cracks.

“CMS is reaching out directly to consumers who have already selected a plan, to let them know to be in touch with their insurer to pay their first premium to ensure that coverage kicks in,” he said.

Asked directly by reporters if the White House could assure customers who have signed up that they will definitely have coverage by January 1, Carney appeared to suggest it was up to individuals to double-check for themselves.

“What I would say is that CMS is reaching out to those who have enrolled to make sure they know the steps they need to take to ensure coverage kicks in,” he replied.

“If consumers are not sure if they are enrolled they should call our customer call centre or the insurer of their choice to make sure they are covered byJanuary 1st.”

The issues with the back end of the website have been known for some time, but White House troubleshooter Jeffrey Zients admitted on Sunday that technicians had prioritised fixes to the consumer-facing part of the site in the initial weeks after launch.

Those attempting to enroll can currently select one of the plans listed on the site, enter their information and determine if they are eligible for subsidies. However, in order to pay for the selected plan, they are supposed to be redirected to the insurance provider and submit their payment information directly.

Coverage and payments facing delay

Some insurers are receiving phone calls from people who believe they are enrolled, but have no record of them. Other insurers are receiving applications, sometimes incomplete, but no payment information.

In one recent case, insurer Blue Cross Blue Shield in North Carolina received more than 500 applications in October but no payment information, which resulted in no actual enrollments.

A report obtained by local North Carolina TV-station WNCN shows how Blue Cross Blue Shield is concerned that those attempting to enroll have not been making payments when redirected – because of a broken hyperlink.

Of the 570 applicants, only 100 have been successfully redirected to the payment options, but none have actually completed the payment process, according to the report.

Experts on commercial payment systems say back-end challenges of this type are not uncommon, but need to be seen as a vital part of the consumer experience.

“One of the 'pain points' of payment is entering information, and that takes time. The focus [in the private sector] is on reducing those steps,” said Jason Oxman, CEO of Electronic Transaction Association. “Once [consumers] have decided on their purchase, payment should be made as easy as possible.”

Some of those involved in earlier healthcare websites say it could cripple Obamacare if it is not ironed out quickly.

"If insurers cannot track and collect premium dollars each month, the extra work of doubling back with customers and insurers will frustrate consumers and delay coverage. And a mounting backlog could eventually compromise the fiscal integrity of the exchange,” said Jon Kingsdale in an op-ed for Washington Post. Kingsdale oversaw the Massachusetts state exchange from 2006 to 2010.

Kingsdale said the backlog will particularly discourage healthy young people from enrolling. Since these "young invincibles" were to supposed to help subsidise older and sicker enrollees, there is a likelihood that the premiums for 2015, which are set as early as spring 2014, will increase.

Others argue these are temporary challenges that should not deter customers in the long run, nor affect the overall success of the initiative.

Dan Schuyler, Director and healthcare consultant at Leavitt Partners, said that while consumers that don’t submit payment to the carriers will not be enrolled in an health plan, he anticipates that very few consumers who enroll will not pay.

However, the uncertainty is another embarrassment for the White House, which was also dealing with overwhelming consumer demand after its much-publicised “fix” led to 380,000 visits on the first morning and many reported error messages.

“We believe that this website is, and will, function effectively for the vast majority of users,” added Carney. “But the work is not done, as we have been saying for some time, [and] there will be continuing issues to address.”

Consumers looking to enroll in health insurance can just do it all directly with the insurer, but the downside is that by going to the insurer and bypassing the exchange they cannot see if they are eligible for a government subsidy – or apply for one.

The White House claimed on Monday that the issue of providing information to insurers, through so-called 834 forms, was now being tackled.

“CMS has daily conversations with issuers to get feedback from them. We have instituted a number of significant fixes to the 834 forms. We believe the majority of fixes have been made, including significant ones over the weekend,” said Carney.

“We are going to continue to work with issuers to make sure whatever remaining problems exist are addressed and fixed.”