From your Agent screens, click on the + button in the top right-hand corner, select New Client and then choose the Self-Assessment option.
Either choose to manually add a new client or you can batch upload multiple clients by downloading the CSV template, populating it and then upload via the choose file option.
Once you have successfully added a client/s (either manually or batch upload) they will then appear within your clients list under the Service Type ‘Self-Assessment’.