Date is different to how it was originally entered:
Example of scenario from users perspective:
A job was added to the diary on 25th July 17
The job took place on 28th July 17
A reminder was added by the system for 20th July 17
The actual job was created on the 20th July, but the diary event was created 25th July.
When you first create a job against a customer who doesn't have a service reminder date, the date is added (assuming you check the 'Is a service' box). The service date is added to the 20th July as at this point, as Commusoft doesn't know what date you completed the service (as you may or may not get access etc) the service date will show as 2017. Once the job is completed though, i.e. final invoiced or free of charged you'll be asked when the service happened and will update next years service reminder and show for 20th July 2018.