Hi Sara and Welcome to the forum, you might want to have a look at the following FAQ which explains where everything is
Welcome to Benefits and Work The absolute time limit for requesting MR is, as it has always been, 13 months. However, DWP only have an obligation to accept the request up to one month. After this the claimant must show 'good cause' for the delay and this becomes more difficult as time goes on.
The change has been in allowing the claimant to proceed to appeal if the MR request was late and DWP refused to accept it.
If you have further questions please reply to this message and we will do our best to help