This is how it would look like:
Its quite some numbers I have to admit. Another idea would be a tool tip on mouse over of a cell in the annual rate column, which then additionally shows the the corresponding absolute rate.
I don’t want to change the content in the duration column but basically “apply” it as end date and maybe to adapt from that point using the calendar tool. I can imagine that people open this dialog, see that they can get 0.165% on their NBT if they park them for the next 11.4 days and decide to take this offer. Then it would be very nice to be able to take this offer with few clicks, and I thought a double click on a row in the “Current rates” box would be convenient.
By the way, I think it is quite confusing that the user is able to change the values in all the tables. Is this on purpose? There is surely some parameter which can be provided in the QT resource file to make them read only.