Full definition
Bank margin is one of the two components of variable mortgage interest (the other is WIBOR or WIRON). The margin is negotiated and fixed at contract signing, and, subject to very narrow exceptions, stays constant for the entire repayment period, unlike WIBOR which fluctuates. In 2026, mortgage margins for PLN loans range from roughly 1.7% to 2.5%. The margin depends on: down payment (higher deposit = lower margin), BIK score, loan size, cross-sell products (current account, card, insurance), existing relationship with the bank. A 0.5 p.p. difference (2.0% vs 2.5%) on a 400,000 PLN / 25-year mortgage costs roughly 130 PLN per month and ~39,000 PLN over the full term, which is why margin is one of the most important items to negotiate.
Concrete numeric example
Offer: WIBOR 3M + 2.2% margin = 7.49% interest. Ten years later, if WIBOR falls to 3.5%, the total rate becomes 5.7%. With a 2.5% margin the rate would stay 0.3 p.p. higher for the full term, regardless of WIBOR moves.
Related terms
WIBOR
The reference interest rate at which Polish banks lend to each other on the interbank market. The base for variable-rate mortgages in Poland.
Interest rate
The annual percentage paid on the borrowed principal, fixed or variable (WIBOR + margin). Excludes fees; total cost is captured by RRSO instead.
