My question is concerns some shop here in Australia. Sometimes here in Australia shops offer to buy a product with for example 3 years interest free. After the 3 years and if the customer did not pay the full price an interest will apply for the remaining of the prise. Is that Ribaa?

All perfect praise be to Allaah, The Lord of the Worlds.  I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

These types of transactions are not permissible because if the buyer delays in paying the cost of the product, interest will be added for the delay, and this is Ribaa (interest or usury) in itself and is forbidden. This is similar to the famous saying of the people of the time of ignorance before Islam, “Either you pay the debts or pay interest.”

Additionally, the Prophet, sallallaahu ‘alayhi wa sallam , cursed the one who consumes Ribaa, the one who gives it to others, the one who records it and the one who is a witness in the transaction. He, sallallaahu ‘alayhi wa sallam, said: “All of them are equal in sin.” [Muslim]

Allaah Knows best.