From the story here:
The cost-sharing funds, estimated at roughly $7 billion for this year, pays for low-income consumers' out-of-pocket medical expenses. Under Obamacare, insurers are required to offer lower costs for these services, for which the government then reimburses them. If they do not receive the funding, they must still offer discounts, and without an action from Congress they would be likely to sue for the money.
