The best time to desex a cat is typically between 4 and 6 months of age. This is when most cats reach sexual maturity, and it's recommended to have them spayed or neutered before they can reproduce.
Desexing, also known as spaying (for females) or neutering (for males), involves removing the reproductive organs, preventing the cat from mating and producing offspring. Apart from preventing unwanted pregnancies, desexing can also provide several health benefits and reduce certain behavioral problems in cats.
In some cases, local councils may offer reduced fees for desexing cats if it is done prior to a specific age. You mentioned avoiding council fees by desexing before 4 months of age. It's important to check with your local council or animal welfare organizations to determine the specific guidelines and requirements in your area. The regulations regarding council fees and desexing age can vary from one location to another.
To ensure the best course of action for your cat, it's recommended to consult with a veterinarian. They will be able to provide specific advice based on the individual needs and health of your cat, as well as any local regulations you need to consider.