Some consumers who buy their health insurance through the Massachusetts Health Connector could see their premiums rise by more than 25 percent next year if the federal government makes good on threats to end certain subsidies or if the fate of those subsidies remains unclear next week.

With uncertainty around federal health care changes looming and the start of an open enrollment period right around the corner, the Massachusetts Health Connector and Division of Insurance have prepared two sets of rates for 2018 to account for the possible loss of revenue that would affect federal subsidies for plans offered through the Connector.

The Connector must settle on one set of rates in less than a week and is preparing to advise members to shop elsewhere for coverage if it must use the set of higher rates that assumes the federal government stops making monthly cost sharing reduction (CSR) payments.

The Commonwealth Health Insurance Connector Authority Board had canceled its September meeting – at which it typically approves plans and rates for the coming year – as the state worked with carriers to chart a pathway to deal with the uncertainty and Health and Human Service Secretary Marylou Sudders said Gov. Charlie Baker has been lobbying for the continuation of CSRs, as recently as Tuesday evening.

“Faced with this uncertainty and challenges, the Health Connector and Division of Insurance have worked extremely closely with carriers all summer to develop two potential pathways with the guiding principle of protecting members first and always,” Sudders said. She said the loss of CSRs “could put our members and the coverage gains Massachusetts has worked so hard to achieve at risk.”

The fate of the CSR subsidies partially hangs in a lawsuit, House vs. Price, initially filed by House Republicans against the Obama administration. The Trump administration has also threatened to end CSR payments as a way to sabotage the Affordable Care Act and force Congress to pass health care reform.

One set of rates assumes that CSRs are eliminated and would set higher rates for the Connector’s silver tier of plans. Sudders said that option “would seriously disrupt coverage for up to 80,000 members.” The second set of rates does not take the loss of CSRs into consideration.

Health Connector Executive Director Louis Gutierrez said the Connector administration must decide no later than Tuesday morning which set of rates will be uploaded in order to meet deadlines associated with the Nov. 1 start of the open enrollment period. The decision does not require a board vote, but the Connector board will be notified of the administration’s decision Tuesday morning.