How did you determine the $39k after taxes. Are you considering 2 parents and 2 dependents? They could probably get covered under Covered California also.
I think the dependent has to be a qualified relative and there is a very low income threshold. And with the tax reforms I think there is not much benefits.
So at that point, maybe its 2 parents and 2 single adults so you cannot combine their income for tax purposes. Maybe each makes $15k which is a very low amount for paying any taxes.