In the Plans tab, open the project that contains the action you’d like to report cost for.

On the action you’d like to report cost, click on the context menu  and on “report cost.”

Upon opening the action, you may report the cost under “costs“. Fill in:

 

After filling in the information, click on “Report.”

What if more costs are reported for the same action? The reported cost accumulates. And all the records are kept.