Rental Property Safe Harbor Rules

Hello, I have three rental houses, two had net incomes and one had a net loss in 2024.  I have the rental houses for over 10 years and have not used the “safe harbor” rules for rental properties.

 

  1. Can I start using the safe harbors rules even if I have not used it in the previous 9 years?
  2. If I can use the safe harbor rules, can I use it for one year, and don’t use it for another year?
  3. Since I have two houses that had net incomes and one had net loss, can I use the safe harbor rules only on the two houses that had gains, but not use the safe harbor rules for the one house that had a loss?  Or do I have to use safe harbor rules for all three house?