Its just like gambling, If you fix at 5.23 and the rates go up you could end up paying 5.5 upwards depending on the rate increase, the tracker is always cheaper, the reason no-one has given you an answer is that there is no answer, It depends on your circumstances, common theory is that the base ECB rates wont go above 4.5% in that case you would be probably paying around 5.25 or most likely more, If you want my opinion I would fix as there has been talk of the banks raising tracker rates regardless of the ECB rate changes as money becomes more difficult for them to borrow with the current credit squeeze.