On December 28, 20x5, Tenant mailed the check to Landlord by certified mail, return receipt requested. The postal carrier tried to deliver the check to Landlord's home on December 31, 20x5, but was unable to do so because Landlord had left early to celebrate New Years. The postal carrier merely leaves a Notice of Attempt to Deliver Mail at Landlord's house, telling him to pick up the letter at the post office.When does Landlord have to recognize income?