Any assets used by a business (and rental property is a business) on a recurring basis in the production of income is required to be depreciated. Period. However, furniture can qualify for the sale-harbor expense deduction if it's cost was less than $2,500. If you paid less than $2,500 for the furniture in 2019, then I would suggest you expense it and be done with it. Otherwise, you must depreciate it starting on the date it was placed in service.