Login to the Care Diary login page and go to Participant > Profiles using the left menu. All the Participant profiles are displayed in the List tab. Click on the participant profile you want to assign accounting code to.

Then in the participant profile tab find the accounting code field

Click on the refresh icon to fetch the latest customers from Xero

Once the fetch/sync is successful, you will see a success message

Then search for the customer you want to map this participant to

Then select the customer from the list and hit Save button

That's it. You have successfully assigned a Xero customer to a participant in Care Diary