If you need to make an edit to previously generated invoice, you have two choices:
If your books are not closed for accounting purposes (e.g. GST reportings) AND you have not received any payment to the invoice, you should be able to simply edit the original invoice and make suitable changes such as applying discounts, or making other fee/cost changes.
If you need to make edits to previously issued invoices or need to write off remaining amounts, use “Invoice Change/Writeoff” function instead of directly editing the original invoice.
This distinction is important as in Accrual Accounting, invoice amounts and taxes become collected on the day of issuance. Examples when “Invoice Change/Writeoff” should be used:
To add amounts to a previous issued invoice such as Late Fees, Finance Charges
To discount a previously issued invoice
To writeoff remaining balances
Invoice Change/Writeoff function lets you increase or decrease any invoice component amount. Note that Invoice Change/Writeoff function does not do any tax calculations. You need to account for these issues when using this function. Consult with your accountant. Click here for a detailed article on how to use Invoice Change/Writeoff function.