I have removed an invoice line from an estimate from one invoice and would like to add it to another invoice, a month later, that I've already created.

Hi there, Nik. The option to add unbilled estimate lines to an existing invoice is unavailable.

The reason you're unable to see a billable item in the right-hand drawer is that the billable pane only displays time and expenses marked as billable, not estimate lines. Once an invoice is saved, QuickBooks doesn't allow for the retroactive linking or adding of additional estimate lines. The system treats the invoice as a separate, finalized transaction.

To include a line from the estimate in your existing invoice, you'll have to manually copy the line item details from the estimate and paste or type them into that invoice.

If you have any additional questions, please feel free to revisit this thread.