Does the Subsidy have to be PAID BACK?

There's no such thing as a free ride!! What would happen if people who received a subsidy under Obamacare discover part of it or all of it will have to be paid back in 2015 when they do their taxes for 2014? Will they feel it was a benefit or wish they had taken the penalty? What does a person do who have insurance and the deductible is high? Or that person has out of pocket expenses? What is your Plan B?