New tax season wrinkle: Health law reduces tax refunds for some while others receive a boost

As the April 15 tax deadline nears, people who got help paying for health insurance under President Barack Obama's law are seeing the direct effect on their refunds — hundreds of dollars, for better or worse.

The law offers tax credits so people without job-based health insurance can buy private coverage. These subsidies are tied to income, so consumers have to estimate accurately what they'll make for the coming year.

And that's been a challenge for lots of people.

Earlier in the filing season, the tax preparation company H&R Block reported that 52 percent of its customers who got health insurance subsidies owed money back. Repayments averaged $530.

On the other hand, about one-third of customers with subsidies overestimated their incomes. Their refunds went up by $365 on average.