Factors to consider in the decision:
1. Is any bank likely to offer a term longer than 4 years @ 2.6%? If so, what is it likely to be. Bearing in mind the current term with Ulster Bank is until 31st March 2022, so more than 4 years
2. Where are interest rates likely to be in March 2022 - that is the big question that no one knows
3. Do you want to overpay, and if so by how much. Both banks limit the amount of overpayment
4. How big is the mortgage and what is the opportunity cost of waiting to see what happens next with the banks ... how much is it costing you per month to wait?
5. How long have you left on your mortgage? If you have ~10 years, is it worth turning it into a lifetime fixed rate? If not, what rate would you be rolling onto from both banks? This needs to be crystal clear given the whole issue with trackers at the moment
6. What is the break cost to get out of both mortgages, how are they costed and can you get clear numbers from them on this, especially KBC after the 4 year bank (for comparison)
Personally, my crystal ball thinks BOI will reduce the rates of their 10 year fixed to around 3.2%, continue to offer the 3% cashback, so still leaving it slightly more expensive than KBC, but better cashflow in the short term. I am not sure any of the other banks will react to this
Option is to start the switching process with KBC and see where you end up, as it will take a while to go through the process and see if any bank reacts in the next 4-6 weeks ....