The health law's insurance subsidies — administered as refundable tax credits — will begin to flow next year. But by 2017, they'll be the second-biggest healthcare tax expenditure at $96 billion, Hatch said.
The ACA provides subsidies on a sliding scale, based on income, to help pay for private health insurance. The subsidies are only available to people who purchase coverage through a new insurance exchange and do not get their coverage through an employer.
The tax exclusion for employer-based healthcare benefits is the biggest expenditure in the tax code.