If you are selling a property with a swimming pool or spa in NSW, the contract for sale must have a certificate of compliance attached, or a certificate of non-compliance, or a relevant occupation certificate together with the certificate of registration. Without one, the contract may be incomplete and the buyer may be able to walk away from it.
If you are leasing, a valid certificate of compliance has to be in place before the tenancy starts. A certificate of non-compliance will not do for a rental.
And if council has issued you a notice about your pool barrier, you will need an inspection to sort out what has to change and to get the certificate once it does.
A certificate of compliance is valid for three years from the date it is issued, so it is worth checking what you already hold before you list the property.