Too difficult to say. Depends on whether you have had leave that month, your personal roster stability that month, whether you had any nightstops at other bases etc etc
If you had a month of working from another base then you are on duty pay continuously from when u check-in at your home base to when you check-out back at your home base. On the other hand if you are only working out of your home base all month the the duty pay is a lot less obviously.