You can generate an invoice with all the required information by yourself in your Account area.
Open the Account > Billing page. In the table of all purchases there will be a “Generate Invoice” link for every payment you made.
Following the link, a new popup will be opened where you can configure all the details that you want to be included in the invoice. There you can also set up the “Tax / VAT Number” value, if needed.
Clicking the “Save Billing Details & Generate Invoice” button will generate an invoice that you can print.