Your account balance is the accumulation of all fees associated with your orders, which includes Hosting (Monthly Plan) Fees, Service Fees, Shipping Fees, and Production Costs.
If you are using your own payment method(s), which we highly recommend, the total amount your customers spend goes directly to you. Since we do not receive the money on your behalf, that number is not added into your account balance. However, since the fees mentioned above come from us, this is factored in and deducted from your balance. Thus, it will show negative as soon as orders are placed.
At the end of every month, GotPhoto will prepare an invoice with all fees accumulated during the month. If any balance remained from a previous invoice (whether positive or negative), that will also carry over into the next invoice.