On the add asset form, when you select the Asset Type is Superannuation we allow you to Edit your historical concessional contributions. You can either us the Draggable Graph to provide quick values or use the "Advanced" Edit Asset view to provide more fine grained inputs via the table.

This then impacts your Unused Carry-Forward Concessional Contributions

Advanced View

Your carry forward concessional contributions or unused concessional contributions cap for the previous five years, can be obtained from the ATO using MyGov.

Step 1

Login to MyGov (https://my.gov.au/)

Step 2

Access ATO

Step 3

Click the Super dropdown in the top menu and select either Concessional Contributions or Carry-Forward Concessional Contributions

Step 4

Select last year and you should see a box like the image below. Expand the "Show Details"

Step 5

From the show details section you can see a column for Concessional Contributions.