The "To Date" total is how much money you have made this month so far (not the total you have made since starting the game). The monthly total is the predicted amount you will have by the end of the month.
At the beginning of the month you get charged lots of fees, like gate rental and aircraft leases, however you get the ticket revenue progressively (every game day). This means you will often be in the negative at the beginning of the month. Assuming you don't do anything, you should make about as much money by the end of the month as is predicted.
