Is there any way to make a note on a completed return, that, when transferred to the next year, will pop up before you can enter any new data?

Theres a place in the Client Status to include Permanent Notes, so if you re-trained your brain to open the Client Status screen with the button at the very top of the Fed info worksheet before scrolling down, you'd see the notes.....but I dont know of a way to have a popup note appear when opening a client file.

Depending on what exactly you want the notes for ...

You can double click most data fields and get that little detail worksheet.  Anything you write on the left side will carryover to next year.  And because those notes from the left side are carried over, the data field in the next year shows zero, rather than being blank, so that can alert you that there is a note about that item.

Again, that won't solve all things that you need a note for, but it may help with some line-specific notes.

I always add a note for the name  box if I need a note, then when I open clients I take a quick look if I have any notes for that client, and they carry over year to year

Have you ever used that red exclamation point that appears on the left of the Home Base? It's also used on an entry block by right-clicking for "Missing Client Information."

I don't use it, but does it carry forward from year to year?