Variable interest rate (oprocentowanie zmienne)

An interest rate that is the sum of a reference rate (e.g. WIBOR or the index that is to replace it) and the bank's margin. When the index rises or falls, your instalment changes after the next update.

The index is updated on dates set in the agreement, while the margin usually stays the same for the whole loan term. With a variable rate, the bank calculates your creditworthiness with a buffer for rising rates, so it may come out lower than with a fixed rate.