Before we begin let us go over what a prepayment is. A prepayment is a payment you are taking in that you are not yet applying to an invoice as the client may have not been invoiced yet. If you are paying a specific invoice you want to create the payment directly on that invoice as per the info linked here.
Click on the plus icon and choose the Record New Prepayments option.
Fill in the the fields you require.
Enter a qty of 1 and the amount of the payment. You can also have BusinessMind calculate the tax rate on the payment or simply select No Tax. (if you do not see a no tax option please email support@dcit.com so they can assist you).
The description field located below the payment line is for the payment type
Click the save icon to save the prepayment.
Once the prepayment is saved you can choose to allocate it towards existing invoices. You can do this now or at a later time if you would like.
From the prepayment detail view click on the gear icon
Choose the Allocate Credit option
This will display all open invoices that the prepayment can be allocated to.
You can allocate a prepayment over multiple invoices
Fill in the Amounts then click the Allocate Credit button to save