This Self Assessment Tax Payment Reminder can only be sent to UK clients. 

To set up an SA Tax Payment Reminder navigate to the client's file, under Services Required ensure the Self Assessment Tax Return service is ticked. Navigate to Accounts and Returns Details and fill in the fields Tax Amount Due (Jul, Jan or Jul) & Tax Office. You can add a payment amount to one or more fields

Click Update Client and refresh the page and at the top of the Accounts and Returns Details section a button will appear allowing you to send an ad hoc email to the client.

To automate the payment reminder navigate to Settings > Automation Settings > Tax Payment Reminders and tick Automatic Tax Payment Reminders, add days to the SA Tax Days field/s then click Save Settings:

If your client informs you that they have made the payment, to stop the reminders navigate to their client file and remove the figure completely from the relevant Tax Amount Due field then click Update. Client: