“Millions of people who take advantage of government subsidies to help buy health insurance next year could get stung by surprise tax bills if they don’t accurately project their income… What happens if you or your spouse gets a raise and your family income goes up in 2014? You could end up with a bigger subsidy than you are entitled to. If that happens, the law says you have to pay back at least part of the money when you file your tax return in the spring of 2015.”