Federal regulations require that an awardee file a regular U.S. patent application on any "subject invention" to which it elects to retain title within one year after election of title or, if necessary, before the end of any statutory period during which valid patent protection can be obtained in the United States after a publication, offer for sale, sale, or public use. The following sections of 37 CFR 401 explain this requirement:
37 CFR 401.2 - Definitions 37 CFR 401.14 - Standard Patent Rights Clauses "Invention Disclosure"
Law - Initial Patent Application Filing Date