We have a situation where we need to make Sales Invoice Adjustments after the invoice is posted. Mostly this occurs because tax is calculated wrong and the customer is refusing to pay the invoice that they receive. What is the correct procedure to handle adjusting an invoice?
Load a credit note, and re-invoice. This ensures the credit handles the incorrect tax and the posting dates are valid, whilst the invoice posts everything correctly. A pain, but these adjustments should be the exception - if they are the norm you have a very different problem.
We use the Service Module and the FSA application (Field Service Automation) by Hitachi (formerly Iteration 2). The way the invoice is done is actually through the Project module and project invoicing.
You will need to raise it against the project itself, either as a journal or a transaction. As the Hitachi is an add-on it is outside of this reply - there maybe a way to do it through that, but you would need to ask your partner. The return order would create a credit note, but you can create one without, not sure if you can do this from within a project from the top of my head, but depending upon what you want to affect you have options, there is also the adjustment process, but as you have created and posted the invoice it is too late for this