In 2016 and 2017, I received long term disability payments. In 2018, I repaid over 21,000 of these benefits. At no time did I receive an amended tax form to reflect the difference.

After researching this issue a little, my interpretation is that I cannot file a 2016 or 2017 amended return to correct the income, but rather I should file I Claim of Rights Credit (Claim of Right- IRC Section 1341) on my 2018 return.

Basically from what I understand, I should calculate how much less I would have had to pay in taxes during 2016 and 2017-when I received income that was later required to pay back, after subtracting the payback amount. Then I can claim the difference as a credit.

Here are my questions:
1. With the new 2018 form, what line and schedule should I write in the credit? And is it accurate that I need to just write in the credit amount and the phrase "?I.R.C. 1341?
2. Is there a form for this credit or any additional documentation I need to include? I could not find anything on this but seems odd just to calculate an amount and write it in.
3. Is there anything else important to note regarding this claims of right credit that I might not understand?
4. Is there anything I can do regarding this credit to try to prevent an audit? My claim is legitimate but came across an IRS memo that some people are falsely using this credit, and no one wants an audit in their life.
5. How can I get state of Michigan and city of Detroit taxes overpaid back as well? I could not find anything on this.

Thank you so much for your help!