How can I find the next date for my 90 days notification after approval?

The user has recently had their 90 days notification approved online and is seeking ways to find out the next reporting date. Comments suggest that the user should count 90 days from their last due date, as the online system might not display the next date. Another comment indicates that there is an attachment available with the approval notification that contains this information. Concerns about the reliability of the online system are also mentioned.