DB Design Up Front

I am trying to create a Preventive Maintenance Program for my facility,

I will create maintenance tasks:
[ID],[Dept.],[Machine],[Task],[Frequency],[Completed Date],[Due Date]

Simple tasks,

Up front design help,

I will want the task to stay in the task table and the Due Date to be calculated combining the [completed date] & [Frequency]

Simple not a problem,

Here is my problem:
I will need to create a task history table that will contain the Task details and the Completed date each time I complete the task; therefore my thought is that i will need to send the task detail to a history table each time it is complete, so I thought Append Query; but the problem is that it appends all of the records in the task table each time you run it including the tasks that have been appended on previous query runs.

any thoughts on how to capture the task details for a specific record and send them to a history table ?