NSF has published guidance on their website (links below) to advise applicants of shutdown impacts on existing proposal deadlines.

• The implementation of the revised NSF PAPPG (NSF 19-1) has been It was scheduled to be in effect starting today.  They will post a new implementation date on their website as soon as practicable.
• The Deadline dates for the solicitations listed at the links below have been extended, however the new deadline dates have not been identified yet.  Within 5 days of resuming operations, the websites below will include revised deadlines and the deadlines listed on the actual solicitations will be updated.  Currently, these are the only solicitations with a deadline that will be extended (best to check the webpage regularly).  All other deadlines remain valid.

https://www.nsf.gov/shutdown/grantees.jsp

https://www.nsf.gov/bfa/dias/policy/postshutdown.jsp