What is rental property depreciation?
The IRS considers that buildings wear out over time. Even if your property is appreciating in market value, the tax code lets you deduct a portion of the building's cost each year as a “depreciation expense.” This is a non-cash deduction — you don't write a check for it, but it reduces your taxable rental income.
For residential rental property, the IRS requires straight-line depreciation over 27.5 years. The formula is simple:
Annual depreciation
(Property value × building ratio) ÷ 27.5
The IRS requires you to separate land from building value. Land is not depreciable. A common split is 80% building / 20% land, though the actual ratio depends on your local market and appraisal.