I worked full time and had insurance through my employer from Jan thru Sept. In October I quit my job and got a part time job to care for my mother and health insurance was not offered by my employer. I signed up for a plan through the exchange and entered my monthly income and qualified for a subsidy. But now, when I do my taxes and enter both W2's from the full time and part time job, it calculates that I wouldn't qualify for the amount of subsidy I received so wants me to pay it back for those 3 months I received subsidy. That doesn't make sense to me. I lost coverage through my employer and took a huge cut in pay. That is why I qualified for special enrollment and subsidy in the first place. Based on the current (supported by paystubs) monthly wages.
Your premium tax credit is based on your income for the entire year. When you applied for the premium tax credit you had to estimate your total income for the year. When your tax return was filed your premium tax credit was computed on your total income, W-2s, for the year not just what your income was during your 3 month coverage period. That is why your premium tax credit was not allowed.