At present the Account Preparation task is generated with the final CRO B1 annual return date as the deadline date. There is no option to change the deadline date, such as for regulated entities whose accounts needed to be signed off within six months of the year end date, which is normally earlier than the CRO deadline.
I would recommend that there is an option created to edit the Account Preparation deadline for individual clients, so that the tasks can appropriately reflect the correct deadline.