Under Obamacare, increases in household income can result in increased premiums.

My wife was on it for a short while before she was old enough to enroll in Medicare. Our annual SS C.O.L.A. raise which amounted to only about $35 - $40 a month total for the both of us that year caused her monthly premium to increase $120.

I'll never understand nor could they explain why a $40 a month raise warranted a $120 a month premium increase.