Is March 31st 2017 the last day when USCIS would take a decission on your case or can it be longer?

Hi

 My case was picked in lottery in April 2016. Would March 31st 2017 be the last day when USCIS would take a decission on H1B 2017 case or can it take longer? The case is currently in RFE.

You may never know, they can take longer under normal processing. You may upgrade to premium processing if you would like, to get decision in 15 days.