If you qualify for premium tax credit, you may also qualify for cost sharing reductions as well.
These are available for individuals and families with household income of less than 250%. Native Americans as defined in the Federal Indian Self Determination Act sec 4(d), are eligible for a special set of cost sharing reductions when they have household income less than 300% of the federal poverty level.
These benefits have the effect of reducing deductible & out of pocket limits and are available only on Silver plans but effectively increase the benefits so that they can be equivalent to a gold or silver plan.
Here is an example of how these cost sharing reductions might affect an individual age 45.
In other words, as your income declines both your premium cost and your out of pocket risk get smaller.