To accomplish this, follow this steps:

1. Create your date field "BaseDate" (in my case I created a Date only field)
2. Create a calculated field "BaseDatePlus1" with the following formula =DATE(YEAR(BaseDate)+1,MONTH(BaseDate),DAY(BaseDate))
3. Create your other date field "Due Date"(in my case I created a Date only field)
4. Now create a SharePoint designer workflow that set a field in current item as follows: Set Due Date to CurrentItem:DatePlus1 and configure it to run every time you create an item in the list (or whatever you want)

Later, you can hide the calculated field from your form using SharePoint Designer.

Hope this helps.

To accomplish this, follow these steps:

1. Create your date field "BaseDate" (in my case I created a Date only field)
2. Create a calculated field "BaseDatePlus1" with the following formula =DATE(YEAR(BaseDate)+1,MONTH(BaseDate),DAY(BaseDate))
3. Create your other date field "Due Date"(in my case I created a Date only field)
4. Now create a SharePoint designer workflow that set a field in current item as follows: Set Due Date to CurrentItem:DatePlus1 and configure it to run every time you create an item in the list (or whatever you want)

Later, you can hide the calculated field from your form using SharePoint Designer.

Hope this helps.