That link doesn't work. I think this is what you are referring to: https://www.marottaonmoney.com/qa-can-a-529-reimburse-for-last-years-expenses/
You have to read it all. That's an old reference to a proposed rule change that never happened. Commenter was suggesting meeting the March 31 date just in case the rules changed.
As others have said, you have to match the distribution year to the tuition paid year.
