I think the keyword here is highlighted below. As far as I can interpret, it is the difference between the rate you borrow at the time you took out the mortgage versus the rate you would get today (from EBS) for the remaining period you have left.
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So if there is 2 years left as per the example above, you'd be looking at 4.90%.. I would expect it to be a negative number in this scenario so would be zero.
It would be best for you to get EBS to confirm your fee just to make sure if it is interpreted corrected and that you can replicate the calculated value they give you.
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