You are correct Form 8275 is not supported by TurboTax. According to the IRS:
How To File: File Form 8275 with your original tax return.
Therefore you will not be able to efile your return.
Here is the form:
https://www.irs.gov/pub/irs-pdf/f8275.pdf
Here are the instructions:
https://www.irs.gov/pub/irs-pdf/i8275.pdf
I did a search in California forms for disclosure. I did not know your reasons for disclosure. Here are my search results:
https://www.ftb.ca.gov/forms/search/Results.aspx?yearselected=12&TaxType=1&KeyWords=disclosure
If you have other questions about this, ask in the comment section below.
