Can a new quotation be copied from an existing invoice?

Hello there, @la33. Yes, you can!

After creating a new quote, you can simply add or copy the details from the existing invoice. I'd be glad to walk you through the complete steps to get this done.
 

First, open the existing invoice. Here's how:

1. Go to the Sales menu.
2. Within the Customers tab, select the name of the appropriate customer.
3. Find the existing invoice. Double-click the transaction to open it.
4. You'll see an arrow on the right side. Click that one to view the quote.
5. Click Add.
6. Select the Copy the lines button. You'll also have an option to create a new invoice.
   

It'll automatically add to your existing invoice. Once done, click Save to reflect the changes. You can review this article to get more information and tips about creating and sending quotes in QuickBooks Online: Learn how to set up quotes in QuickBooks Online. 

Also, you'll want can pull up the Transaction List by Customer report. This contains the exact amount of the linked quotes, invoices, and payments. To learn more about managing reports, you can check these links:

• Customise reports
• Memorise reports

Stay in touch if you need additional help about QuickBooks transactions. Take care and have a good one, Lach!