I switched to QB invoicing early this year. Prior to that I was using excel and my own invoicing template. Can I recreate those invoices in quickbooks?

I appreciate for posting your concern here in the Community, @lynnaeburns. I'll be happy to share more information about billable expenses.

There isn't a need to recreate those transactions in QuickBooks Online because you have an option to manually edit those expenses you've recorded to make sure everything is accurate. I'll show you how.

1. Select Expenses from the left menu and choose the Expenses tab.
2. In the Expense Transactions window, find the transactions to edit.
3. Under the Action column, select View/Edit.
4. Put a check-mark in the billable box.
5. Hit Save and close.

For additional information, you can check this great article:Enter, edit, or delete expenses in QuickBooks Online.

In regards to the dummy invoices, I would suggest creating the exact transactions since this would be reported in your expense accounts. 

For future reference on how to record and remove a billable expense charge in QBO, check these articles:  

• Enter billable expenses
• How to remove a billable expense charge

Let me know if you have other questions in your account. I'm always here to help. Have a fabulous day ahead!

Got it. Is creating a dummy invoice the best way to deal with this or should I create a sales receipt instead. These have been paid already and I don't want to inadvertently send an invoice to clients for work done and paid almost a year ago.

Follow up question. Does it make sense for me to create dummy invoices or should I create a sales receipt instead since I have already been paid. In any case, I don't want my clients to receive anything since the work was done and paid for almost a year ago.

@lynnaeburns 

It depends on how you want to record them in QBO. If you have the transaction data in XLS, consider using an importer tool to migrate the real of Invoices data and Receive-Payment data into QBO.

https://transactionpro.grsm.io/qbo

https://partners.saasant.com/affiliate/idevaffiliate.php?id=5051_2

Just my 2 cents.

Good day, @lynnaeburns. 

Thank you for reaching back to the Community. 

I recommend creating sales receipt since this already been paid. The Sales receipt use for the transactions which has already been fully paid by the customer. 

Let me show you how to create sales receipt: 

1. On the left pane click Sales, then Customers, drop-down arrow under Action and click Create sales receipt. 
2. Fill out all the necessary details. 
3. Click Save and close once done. 

You can view the Sales Receipt created under transaction List. 

For additional details and informations you can check out this articles: 

• Customize your invoices, estimates, and sales receipts in QuickBooks Online.  

• Add a discount to an invoice or sales receipt in QuickBooks Online

 Please get back to me if you have other questions. I'm here to lend you a hand. Have a great day ahead of you!