CiviCRM not changing membership status on time correctly

So in the organisation that I am with we have a membership period that runs from 1 July to 30 June. Our members are then grace until 30 September. They are then meant to go expired on 1 April. However due to the code the change membership status happens at 31 March which is over > 9 months after 30 June if you just go by changing the month number. However it is not actually after 9 months.