The Obama administration said Thursday it would allow millions of Americans whose insurance policies had been canceled to purchase bare-bones plans next year, in another eleventh-hour tweak to the law likely to cause consternation among insurance carriers.

Health and Human Services Secretary Kathleen Sebelius told a group of six senators in a letter viewed by The Wall Street Journal that people whose policies had been canceled because of new requirements under the health law would be allowed to purchase ‘catastrophic’ plans. Those plans had previously been restricted to people under the age of 30 or individuals who qualified for a set of specific hardship exemptions.

Catastrophic plans typically cover three primary-care visits a year and some preventive benefits, but they have few of the other benefits of the law and only cover large medical costs after a high deductible.