I am in a similar situation except that my actual income was lower than my estimate and I'm still having to pay back some of the Advance Premium Tax Credit (APTC) even though the payments I received were calculated by the government based on my income estimate. Here is what I have found out so far. Sometimes the change is because there has been a change in your filing status (more or less dependents) or a change in your address. In my case, it's still just me living in the same house. I've been told that sometimes the APTC has been calculated incorrectly. (Had my taxable income been what I estimated, the APTC would have been off by over 27% - fairly significant mistake in my book.) But I've also been told that I can file an appeal. I live in MN, so my appeal will be going through MNSure, our state's health insurance marketplace. The representative from MNSure that I spoke with this morning advised me to go through the appeal process since they want to make sure, first of all that I have correct information, but to also make sure that there isn't a glitch in their system reporting inaccurate APTCs. If it's happened to me, then it almost certainly is happening to others. My advise to you would be to contact someone through your exchange to find out what is involved in the appeals process for CA. Good Luck!!
