@Heather Hall In order to give you the best and most accurate answers, I would need to see the Federal Depreciation Schedule created by CPA/tax professional. Your CPA/tax professional has a copy and may have given you a copy with your last tax filing. What I can tell you follows:
1. The ADU was a LTR during those 90 days (1/4 or the year). If the purchase price that is assigned to the ADU is high enough, it could have had cost segregation and Bonus benefits on its own. The fact that you stopped renting it in Oct 2021, may have negated those benefits and your Federal Tax Depreciation Schedule will be telling.
2. There is no depreciation available while your family is living rent free in the ADU and/or you are living in the main house.
3. In June '22 when you move out of the main house and begin renovating the main house, the $75K in renovations will be added to y.our basis in the home or expensed depending on what was done and the cost involved.
4. With a cost segregation study, the main house is eligible for Bonus Depreciation on November 2022 at 100%. If you have filed your 2022 taxes with straight-line depreciation, you will need a 3115 481a Change of Accounting Form done to change from straight-line depreciation to accelerated depreciation.
With the Federal Depreciation Schedule and answers to a few questions, I can get you a no cost pretty accurate pre-analysis that you and your tax pro can review and decide if the benefits fit your specific tax situation. Let me know if you have additional questions and/or you would like a pre-analysis/estimate.