Hi Susie27
If you have a social landlord then you will find a To Do on your account for you to action on the first day of the increased rent. Social Landlords have a special portal with which to share data with the DWP.
If you have a private landlord you must report the new rent via a change of circumstances. You are usually asked to upload the letter of rent increase to your Journal.
Let us know how you get on.
David
Nothing on this board constitutes legal advice - always consult a professional about specific problems