Within Teamwork, you can choose to export an invoice from a project to your Xero Online account.
You will first need to enable the Xero integration at site and project level.
Once Xero is enabled, go to the Billing section of your project and select an invoice from the left pane.
While viewing the invoice, click the Export Invoice button in the bottom left of the invoice.
In the export modal, select Xero Online as the export option before clicking Export.
When you choose Xero Online, you will then be asked to select a client from Xero to associate with the invoice. If you do not have any existing clients in Xero, you will need to create one before proceeding with the export.
For invoice type, you can either create a new invoice or add the details to an existing Xero invoice.
You can also add or remove details you want populated in Xero. Each selected detail will be added to the line item description in the Xero invoice.
Click Export to complete the process. Once you go to your Xero account, you will see the invoice listed under the associated client.
For more information, see: Enabling the Xero Integration