I did not recd the 08/Sep/2020 tax invoice yet. Can resend to me. TQ!

Great to have you here, kc35.

No worries, we can manually record the invoice for September 08 in QuickBooks Online (QBO). Then, send it to your customer. 

1. Click the New Plus icon.
2. Choose Invoice under the Customer section. 
3. From Customer drop-down, select a customer name.
4. Enter the Invoice date and Due date.
5. Select a product or service in the Product/Service column.
6. Enter the details in the Quantity, Rate, Amount, and Tax fields.
7. Press Save and close or Save and send when you're ready to send the invoice.

For more details about creating and managing invoices, check out this article: Create invoices in QuickBooks Online. The article also provides you about receiving payments from your customer and customising your invoices. 

Just in case you created invoices without sales tax, just refer to this article to correct them: Correct invoices created without sales tax.

Visit our Manage Customers and Income page for more insights about managing your customer transactions. 

That should point you out in the right direction today. I'm just one click away if you need a hand with running your financial report or any QBO related. I'm glad to help.