Some Medicaid beneficiaries will be subject to higher copayments and premiums for certain services under a new federal rule that took effect last week.

The new rule gives states the choice of whether or not to implement a new method of collecting copays and premiums from low-income residents. Under the rule, states cannot charge more than 5% of a family’s income for Medicaid services. Medicaid beneficiaries living at or below the poverty line may be responsible for copays of up to $3.40, and those at or above the poverty line could have to pay up to 10% of the cost of the service.

Backers of the plan say it will save the federal government $1.4 billion over five years; states could save up to $1.1 billion over the same period. Opponent groups such as AARP say the new possible charges would make it more difficult for the impoverished and elderly to get needed services. Some public health experts have suggested that forgoing medical procedures due to rules like this one could lead to more complicated and costly medical conditions in the future, according to the New York Times.