When we bought a new build, we signed contracts in Oct 05 and moved in in April 07...interest rates had gone up a LOT by then and we were charged the rate that was current in April 07, even though we were made a bank mortgage loan offer in Oct 05, it was the rate applying in April 07 that applied. Fortunately we had decided against taking the max being offered in Oct 05, so were able to absorb the additional 450 euro/month on the mortgage by April 07.