IBI is annual bill that is issued by the townhall in Javea and is for a period of one year from the 1st of January. All property owners, private and commercial have an IBI bill.
When purchasing a property your legal representative will request confirmation from the seller that the IBI has been paid up to date and you will the be advised of the IBI amount on your property.
On top of the IBI bill there is also an annual bill for basura (bin collection). This is small amount again paid annually to the townhall.
There is a system where you can pay both bills by direct debit on a monthly basis.