What is Line 23600 Federal Net Income when filing taxes for couple

Hi,

 

It's my first time filing my own and my wife taxes this year. We used to ask someone to do it for us.

 

My question is during the introduction on filing taxes as couple, it's asking for the federal net income of the spouse (Line 23600). Is this referring to the already filed tax return LAST year? Or we have to ESTIMATE how much would the amount be if we would have to file this CURRENT tax season year? If the latter how can I estimate that and how to compute for it?

 

Thank you.

Claro