I have a new client who sold his rental property in 2022 but after discussing his gain, he said the improvements he made on the property (it used to be his primary home) before it was placed in service as a rental was not included in the home's basis since 2006.  I've read on a few places that you can't use Form 3115 for missed basis but wanted to see if anyone has any definitive information on that.

Thank you!