Santander: Bank Account / Mortgage Interest

[enfable]

I have a mortgage with Santander where I am paying 1% interest.

They have offered me 5% interest (for the first year) upon openning a new current account with them.

Would I be better taking all the mortgage overpayments and placing them in to the current account, taking in to account taxes.

Hope this makes sence.

[factor-fiction]

On the face of it, yes. I'm assuming you are permitted to withdraw money from the overpayments fund and then repay it all back in again at a later date- probably when the 5% deal or the 1% mortgage deal comes to an end