can you attach an invoice to a PO after the invoice has been paid?

Good afternoon carsons,

Thank you for reaching out to the QuickBooks Community. Just to clarify, purchase orders get linked to an expense or bill after the terms have been agreed to, whereas invoices are created from estimates. However, you can issue an invoice after purchase order terms are met as well, but they will not be linked. In the event you may want to send a purchase order, you can follow the directions below:

1. Select + New.
2. Select Purchase order.
3. From the Vendor ▼ dropdown, select the vendor.
4. Review the Mailing address.
5. Enter the Purchase Order date.
6. Select Settings ⚙ on the Purchase Order form, then on the Choose what you use panel, select the link to add your own custom fields.
7. In the Item details section, enter the products you want to purchase.
8. When you're done, select Save and send ▼dropdown.

If you need further clarification, please let me know! I will be around.