Hi Russell

I had given you a simple example but yes what I have implemented does allow part payment again one invoice and full payment against another. The thing is that as in Inv. #2 in your case the extra 100 remains with the payment (as -100) and will be allowed to be adjusted against a future invoice. I have also provided as an advance option to allow say for eg. the above extra 100 to club with another payment of 500 making it a 600 credit (-600) to be applied to a future invoice.

All in all what I am saying is that Inv. #2 should become 0 and the Payment should still show a balance of -100 (or 100 as you best want to display to the user).

Thus, Payment will have 3 internal records in a link table - 400 with id of Inv #1, 500 with id of Inv. #2. So if you sum based on the id of the payment you will have an application of 900 thus, 1000-900 = 100. When in future you apply this to say Inv #3 there will be another link entry no. 3 of 100 with id of Inv #3. Of course this link table has 2 id columns. One if column for the document that is being applied namely payment id, second I have explained above.

Hope it helps.

>You may not have meant it exactly this way, but it appears you are suggesting that the payments apply "in order" against the oldest outstanding invoices. In fact, the customer needs to select how any credits (regardless of how they are stored in the database) are applied against invoices. Also, the creation of credit invoices is quite common, so I wouldn't call that odd. And there are complexities here:
>
>Payment of $1000
>
>Inv. #1 - $500 - $400 applied
>Inv. #2 - $500 - $600 applied
>
>So the entire $1000 is applied, but there is a underpayment on one invoice and an overpayment on another. They have a $0 balance overall, but you still have to determine and address the situation. There is nothing left to apply on the payment, but there is a $100 credit invoice that can be applied to wipe out the under payment on invoice 1. The balance still remains at zero, but now all invoices are marked with a zero balance.
>
>Thanks for your reply.
>
>
>>Hi Russell
>>
>>I have seen such odd principles being used in another application but I would like to disagree. I have not read the full thread so I may be repeating but I think this is not the right way to go about. What is credit is the payment and that is the document / record that should be showing the balance and the remaining of the payment is what has to be applied to another invoice.
>>
>>Invoice #1 1000/-
>>Payment #1 1250/- (adjust 1000/- against Invoice #1)
>>Invoice #2 1750/- (now allow the system to display the Payment #1 1250-1000 = 250/- and adjust against Invoice #2)
>>Payment #2 1000/- (adjust 1000/- against Invoice #2)
>>Payment #3 500/- (adjust 500/- fully against Invoice #2)
>>so on...
>>
>>Hope it helps. I would suggest you think of these as documents, like paper documents they cannot change beyond what they are.