What procurements require a Request for Information (RFI) or Sources Sought Synopsis?
This is actually a great question.
Sources Sought Synopsis: there is only one scenario that requires you to post/publish a sources sought synopsis on the SAM.gov GPE (Government Point of Entry). See FAR 5.205(a) for research and development contract actions when market research does not produce a sufficient number of concerns to obtain adequate competition. That said, many organizations often require (and it is considered a best practice) the contracting officer to publish one prior to using FAR 6.302-1 Only one responsible source... as a justifcation for Other than Full and Open Competition.
Request for Information (RFI): there are no mandatory scenarios that require an RFI be published, it is strictly the contracting officer's discretion on when to use an RFI. Note: there is no "RFI notice" on the GPE, this is done using either a special notice or presolicitation notice. Typically the RFI is used to augment market research when time permits and the acquisition team is interested in learning more about what or how industry can satisfy a requirement. Editorial note: we believe an RFI should only be used when market research is unsuccessful at identifying trends, capabilities, techniques, etc. of industry. Too often we see the government use an RFI instead of conducting adequate market research. Responding to an RFI can be time consuming and costly for industry so it should be used judiciously.