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Setup as follows:
Go to Configure - Patient Payments and add in a payment type called 'Finance/0% Finance/etc'
Also tick 'Percentage Discounts'
Go to a patient, and chart the treatment as it should cost, eg the full £500.
Invoice through as necessary but take no payments.
When the money comes in from the finance company, for example, they will be paying £450, go to the patients payment screen, and take a payment. Enter in £450 and the payment method as 'Finance/0% Finance/etc', and enter £50 in the discount box, and a reason eg Interest/Finance.
Click Process, and it will make the patients balance nil, but will show that £500 was invoiced, £450 paid, and where and how the extra £50 was accounted for.
The above will only work if the INV_DISCNT adjustment type is set for a positive entry to DECREASE the amount:
Some practices may wish to enter the finance payment before the treatment is completed and therefore a invoice may not be present. This will mean an error will appear if trying to add a discount as there is is no invoice to discount as such.
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