To add or edit task categories, go the Account Settings screen and click Edit Settings. Go to the Calendar tab and click Task Categories.
Adding a Task Category
Once in the Account Settings screen, click the black 'Edit Settings' button then go into Task Categories.
Click on the Add Category button to add a task category. Enter the name of the category within the "Category" field.
Automatically repeating tasks
If you'd like to automatically create follow-up tasks, fill in the "Repeat Every" fields. For example, if you'd like a task to be completed every year, enter 1 in the blank and select "year" from the dropdown. Now, when completing this task, a new task will be created one year from the date of completion.
Additional Fields
You can also track any additional information by setting up custom fields. To add a new field, type of the name of the field in the "New Field..." box and hit "Enter" on your keyboard. Now, decide what type of field you want: Short Text, Long Text, Dropdown, Radio Buttons, or Checkbox. If you'd like to require your staff to fill in that field when completing the task, turn on the "Required" checkbox.
Update (03/22/2022):
You can also carry over field data on Automatically Rescheduled tasks. By default the data will be cleared. You can uncheck this box to have data entered into the task carry over to the rescheduled task: