10/10/2011 11:15 am
I would say if, as you have stated the surrender is mutually agreed, the date of the surrender has also been agreed - this will take effect on the date you return the keys or other agreed date and that rent is only payable up to that date.
If in effect all you have done is to agree with your landlord that you want to move out early, and to end the tenancy early, then s/he would be entitled to the provisions of any notice period/lost rent included within the Assured Shorthold agreement. The tenant's notice to quit requirements will be stipulated in the contract, otherwise the tenancy would end on the date given in your Section 21 notice.
Surrender normally means that you and the landlord agree to the termination of the agreement on an agreed date, bringing all terms and ocnditions to an end.