@Waterboy that's a quality question. LOL.
What configuration are you on? Professional or Standard? The two configurations use different reporting tools, so to better answer your question, I need to know your configuration type.
I know that Cognos can report on the paid date, but I'm not sure if there is a standard report or not, but this report would be easy to build. Cognos is used on our Professional configuration.
If you happen to be on our Standard configuration...I believe you can see this data. You'll have to look in the Analytics Home>Standard Content. There will be a few Invoice standard reports in there.