This Corporation Tax Payment Reminder can only be sent to UK companies. 

To set up a CT Tax Payment Reminder navigate to the client's file, under Services Required the CT600 service must be turned on. Under Accounts and Returns Details fill in the fields Corporation Tax Amount Due, Tax Due HMRC Year End (the payment is due 9 months and a day after the date entered here), CT Payment Reference Number and Tax Office.

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 Corporation Tax Days field 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 Corporation Tax Amount Due field then click Update  Client:

The Corporation Tax Payment Reminder fields are not cleared automatically once the payment due date has passed.