Can i use the whole amt that is on line 3 of self employment tax put that amt on line 18

[Just-Lisa-Now-]

L:ine 3 and Line 18 of what form?   

[dkh]

You are talking about Schedule SE - correct ?  I'm guessing yes so --  If the income was for Jan-Dec you are to use only the amount that was income for Mar27-Dec31.  I read (can't find the source now) that an acceptable method is to use 77% of line 3 for line 18.   If all the income was earned after March 27th then yes you can use 100% of line 3 for line 18.      

You probably already know this but the actual deferral is on Schedule 3.  There is a SmartWorksheet in the 1040Worksheet.