Interest rate swap (úrokový swap, IRS)
IRSAn interest rate swap is a derivative in which two parties exchange a fixed interest payment for a floating one linked to PRIBOR. The fixed leg of a 3-, 5- or 10-year swap shows how the market prices koruna funding over that period, and banks take it as the starting point for fixed mortgage rates. In September 2026 the 5-year CZK IRS was roughly 4.5–4.7 %.
Example
With the 5-year swap around 4.6 % and new mortgages averaging 5.00 % in August 2026, banks are left with only a few tenths of a percentage point above their cost of money. When the swap rises by 0.3 pp, the 5-year fixed rate usually follows by a similar amount. On CZK 4,000,000 over 25 years that adds roughly CZK 700 a month.
In practice
Swap rates move every day, and banks follow with new rate sheets (sazebník) after a lag of days to weeks. Česká spořitelna, for example, raised most fixed periods by 0.3 pp from 11 September 2026. Swaps are not the only reason, though: the bank's margin and competition play a part too. If you hold an offer while swaps are climbing, get it confirmed in writing. Watching only the ČNB repo rate and ignoring swaps gives a misleading picture of where mortgage prices are heading. What that means for the length of your fixation is covered in which fixed-rate period to choose.
How it differs
Frequently asked questions
What is an interest rate swap?
A contract in which two parties exchange a fixed interest payment for a floating one linked to PRIBOR. Its fixed leg shows what the market charges for koruna money over 3, 5 or 10 years.
How do swap rates affect mortgage fixations?
Banks take them as the starting price for fixed-rate periods and add their margin. When swaps rise, new rate sheets usually follow within days to weeks.
What is the 5-year CZK swap rate?
Roughly 4.5–4.7 % in September 2026. With new mortgages averaging 5.00 % in August, that left banks only a few tenths of a percentage point above their cost of money.
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