Be careful not to confuse the rules regarding a real estate professional (outlined by @SweetieJean) and the Exception for Certain Rental Real
Estate Activities passive loss rules. If you meet the latter criteria, you can deduct up to $25,000 in losses each year. Essentially, you must actively participate in your rental activities, have an AGI under $100K ($50K if MFS), and some other conditions as described in Schedule E instructions, page E-3,4.
https://www.irs.gov/pub/irs-pdf/i1040se.pdf
