One month after billing a customer, I realized I totally undercharged them. How do I make a new invoice to show the correct charges with their previous payment applied?

Hello Sam60,

Thanks for contacting us here. QuickBooks Online is a hassle-free program that simplifies the way you manage your accounting. I'll be glad to point you in the right direction so you can achieve your QuickBooks goals. Recording your transactions the right way is a good exercise for keeping your books accurate.

To ensure accuracy in your books, I recommend contacting an accounting professional to get expert advice. Doing this will help prevent any future discrepancies in your books. You can also reach out to accounting professionals on our site using this link here. Otherwise, here's an article that shows you how to: Create invoices in QuickBooks Online. 

I'll also leave this question here so other accounting professional members can chime in and share their expert advice. Let me know if you have other questions, I'm here to assist. 

Thank you for your reply. I need to figure out how to properly amend this invoice after it has already been sent and paid by the customer. I need to properly account for the GST as this is a contracting business.

Hi Sam360.

I'd be happy to help you get your invoice corrected to send to the customer with the right amounts owed.

The best way to correct this would be to edit the existing invoice to the correct information. This'll allow you to send the invoice to the client again while still having the old payment assigned to it as a partial payment. To do this you just need to open up the existing invoice by going to Sales>Invoices>Select the invoice>Update the information and click Save and Send.

If you have any questions let us know and we'd be happy to help.

Thank you for your reply. If I made this invoice in January and update/amend the original invoice in March would this affect my January reports?

Thank you for your reply. If I made this invoice in January and update/amend the original invoice in March would this affect my January reports?

Hello Sam360. Since the invoice was created in January, any edits made to that invoice will affect your January balances. The change will also appear on your January reports as well. Let me know if you have additional questions. 

I only handle accounts receivables in my quickbooks. I print off my monthly reports and hand them off to an outside bookkeeper who submits the taxes to the CRA so changing January reports in March would not be a good option. Could I make a "copy" of the original invoice, update the the prices to what it was supposed to be, and then make a credit memo in the amount of their payment, and then apply this credit to the updated invoice? I hope I make sense?

I see what you're saying. I highly recommend trying this out using our Test Drive account that comes preloaded with sample data. This allows you to try different methods of recording transactions to see how they affect your books. You can access the test drive account using this link here. You're more than welcome to keep me posted on how you make out. I'll be here.