HUD Handbook 4350.3 § 5-22

When processing an interim recertification, the owner must ask the tenant to identify all
         changes in income, expenses, or family composition since the last recertification.
         Owners only need verify those items that have changed. For example, if the head of
         household was laid off from his or her job and asks the owner to prepare an interim
         recertification, the owner does not need to reverify the spouse’s employment income
         unless that has also changed. When the tenant signs the certification she or he certifies
         that the information on the report is accurate and current. Additional information about
         the procedures for conducting interim recertifications is discussed in Chapter 7, Section
         2.