I had to evict renters that were hoarders Nov 2023 - it took me months to clean out, get new floors, paint, fix up. HOA then said I couldn't rent out due to HOA rule where only 25% of houses can be rentals. I final was able to rent out Dec 2024. If I can't write off $20K this year can I save expenses to offset next year?
No. Expenses are either deducted in the year that they are incurred or they are added to the basis of the property or they are lost.
In your case you spent 20K on repairs. The portion of that 20K that is actual repairs is definitely an expense for 2024 on your rental property even though it was not rented in 2024 at the time.
The portion of the 20K that you spent that created new property (replaced the porch, replaced the refrigerator, etc.) should be depreciated as rental fixtures separate from the main property.
Keep in mind that any deduction for passive income may be limited on your tax return based on how much other income you have.