Prospective and current cat owners in Tasmania will need to microchip and desex their cats when they reach an age of over four months old from next month.
The new rules are part of several to come from an amended state government's Cat Management Act, including compulsory registration of cat breeders and registration of more than four cats kept at an individual property.
A cat can be exempted from compulsory microchipping and desexing if a vet certifies that such actions would adversely affect the animal's health and welfare.
RSPCA chief executive Jan Davis said these measures would help manage feral and colony cat populations in Tasmania.
Ms Davis said cat containment, such that is required for dogs, would be the next logical step in cat management.
Ms Davis said shelters could expect to see an increase in the number of surrendered cats or the identification of unowned cats as they were removed from the environment.
"There's no shortage of families looking for new pets," she said.
"Any healthy cat that we have has been adopted."
Ms Davis said the legal changes would be a significant change in terms of cat ownership for many and the RSPCA had questions on how the changes would be enforced.
"A lot of people don't believe that cats should be registered or that there should be any limit on keeping cats," she said.
"The biggest challenge, I guess, is the fact that there's no clear pathway for policing this."
A failure to desex or microchip a cat when it is aged more than four months old could attract a fine of up to $8650.
A multiple cat permit will not attract a registration charge this year.