If applying to the National Science Foundation (NSF), requests for an extension are being reviewed by the NSF on a case by case basis. Please discuss the situation with your assigned Oﬀice of Sponsored Projects (OSP) (through your departmental administrator/FRMS) proposal manager. It is recommended that you discuss the situation with the cognizant Program Oﬀicer prior to submitting a request for a proposal deadline extension.
If applying to the National Institutes of Health (NIH), the NIH has advised the research community that applications should be submitted as soon as possible after the deadline. All applications must include a letter of explanation that provides enough detail about the delay in submission in order for NIH staﬀ to evaluate the circumstance. The NIH has indicated that advance permission to submit a proposal after the due date is not required.