HBO could pocket up to $600 million more a year if the network figures out how to put its content online, according to a report from Barclays Capital released Thursday. The analysis lays out a couple of different ways that HBO could sell its programming online without slighting its cable-provider partners.

The report's author, Kannan Venkateshwar, lays out two options. In the first, HBO would sell subscriptions to "windowed" content that would be available six months to a year after it first aired, but at $11 per month versus the $15 cable price. The other option would be to sell digital subscriptions that give immediate access to its shows, but charge an even higher price for the privilege—about $18.

Venkateshwar estimates that the lower-priced package would cannibalize regular subscribers a bit, but between 4.4 and 6.6 million homes would be interested in the $11 per month option. He pegs the $18 per month customers as a smaller base, between 300,000 and 800,000 homes. If HBO offered both these options together, Venkateshwar estimates that the total take would be around $600 million annually. For comparison, HBO's earnings for 2013 were $1.7 billion.

It is no surprise that HBO online subscriptions would bring a huge cash infusion. HBO is possibly the only thing people on the Internet are regularly whining about not being able to access even though they want to subscribe. HBO Go, which gives subscribers access to HBO content online and on several types of mobile devices, is included with a standard HBO subscription.

It's a hard problem for the network in terms of profit, but negotiating with cable providers is likely to be the bigger issue.