Refusal to terminate tenancy with months notice

Question

I am renting property in UK and today tried to give my months notice, however letting agency refused to accept it claiming that they can only accept it on 25th - day when agreement started, and that this is in my contract. What this means that I would have to pay for period of 15 extra days while not living in a property...

EDIT: as per comment

The tenant may terminate the tenancy by giving 1 months notice in writing to the agent on the 25th day to vacate 1 month later on the 24th day of the month

Another thing I just realized that 25 of Dec is Christmas and I don't think they work on 25th! Can they really do this?

EDIT2: My tenancy originally was 6 months and this period has passed, I didn't sigh anything after does this change anything?

Are there any regulations around this? Does months notice means month+ or is it actually a month?

Answer 1

Under an assured shorthold tenancy, when the fixed term expires, it automatically becomes a periodic tenancy (also called a rolling or month-to-month tenancy) if no other action is taken.

For periodic tenancies, the default requirement is:

The notice you give must end on the first or last day of the period of a tenancy, except when your tenancy agreement says something different.

The first day of a period of your tenancy is the anniversary date each week or month of when your tenancy began. This is often the same date that your rent is due, but not always.

(the above taken from this Shelter guide.) The contract merely restates this.

So in other words, yes, this is normal. In this instance, if you give notice on or before 25 Dec, you'll be required to pay rent up to 24 Jan.

However, if the landlord finds a new tenant and their tenancy starts after you move out, but before 24 Jan, then you are only liable for rent up to the start of their tenancy.