Form W-4P Question

I'm retiring May 1 and will start getting my pension in June.  My husband will continue working.  His annual pay is $40,200.  We file married jointly.  We have no other sources of income.  My question is about Step 2 line (2bi) what do I enter on this line?  I've had some friends tell me to leave it blank or put zero I don't know if this is right either.