WASHINGTON — It’s not too early to start thinking about the tax implications of health-care reform.

Did you buy health insurance through one of the exchanges? You might be eligible for a refundable tax credit.

Taxpayers had the option of estimating their 2014 income to see if they qualified for the credit, then having it applied in advance to the cost of the premiums.

“We have an opportunity in the 2014 filing season to educate taxpayers about what they need to do during the year to avoid problems during the 2015 filing season,” National Taxpayer Advocate Nina Olson said.

Her advice to those taxpayers: Keep the exchanges advised if there are changes in your circumstances that could affect the subsidy.

“It could increase if you have another child and you want to be able to get the benefit of that,” she said. “It could decrease if you have a significant pay increase, if your spouse gets a job, if a child is no longer covered on your plan.”

As a result, some taxpayers could end up owing the U.S. Treasury money when they file their 2014 taxes next year.

“It may mean that they would have a reduced refund, and many taxpayers depend on their refunds for various things,” Olson said. “They’ve used them for planning. They use them like savings, so that will be a rude surprise for these taxpayers. And we can avoid it by having them go into the exchanges throughout the year.”

But what about those taxpayers who don’t get refunds — between 75 percent and 85 percent do, she said — or those whose refunds aren’t big enough to cover what is owed if the subsidy is reduced?

In that case, “the easiest thing is you’ll have a refund the next year, and we’ll take it out of the refund the next year,” Olson said. “It’s a debt on the books. It’s an assessed tax, and we can collect it for 10 years and it’s just a computer offset.”