Thank you so much for the advice! All I wanted is file correctly. Please correct me if the following would still be wrong: I will file with half of the cost, half of the proceed (my 1099-S amount), and all the depreciation I claimed in the past years. This will end up with some gain and I will pay tax on it. My son will file with half of the cost, half of the proceeds (the 1099-S under his name) and 0 depreciation. He will end up with a business lose and get some refund. It will be OK as long as it is legal.
The house was bought when he went to school and he asked to have his name on title (also my wife's name), then rented out when he graduated (could not sale by 2011~2012). My son was out of our state at the closing time, but given all right to our attorney. His check was deposited to a joint account with my name (I used it to send him money when he was in school and did not close after he graduate), then transferred back to my own account the next day. There was no intention to share the profit. I did not reject the way they cut the checks hard enough, since I thought I could get the money easily (without know all the tax problem and 1099-S). I have asked IRS help line last March, tried to make appointment with IRS field office, been referred back to IRS help line (only staffed to answer 2018 tax questions in Jan 2019), been told they do not know what to do but have to tell me to read all the IRS online documents.
