1. Go to Configuration > Company Settings, then click on the Invoice Tab

2. Choose Xero from the Accounting Integration option:

3.If you have multiple companies in Xero you can use your specific classification categories to link to different Xero accounts. 

4. Click on the Connect to Xero button, and enter your Xero username and password:

After entering your credentials you will need to confirm Xero access by clicking Confirm Xero Connection.

5. After logging in you can either use the standard Single Set of Revenue Accounts Only or link multiple Revenue Accounts based on your classification categories. 

6.  Once you have chosen your Revenue Accounts you will need to link the Revenue Types to a specific revenue account in Xero.  After clicking on Link you can then select either an existing account or create a new account.

7. Once the Revenue Account has been linked you can customise the Invoice Line Description.