TL;DR
- Residential rental property is depreciated using the straight-line method over a 27.5-year recovery period under the Modified Accelerated Cost Recovery System (MACRS). - Only the building's cost basis is depreciable; land value is excluded from the calculation entirely, since land is not considered a wearing asset. - Depreciation is modeled as a non-cash deduction, meaning it reduces taxable rental income on Schedule E without requiring an outgoing cash expense in the year it is claimed. - Assuming a $275,000 depreciable basis, the annual straight-line deduction works out to $10,000, before accounting for the mid-month convention adjustment in the placed-in-service year. - Depreciation recapture at disposition is generally taxed at a maximum rate of 25%, a variable that financial modeling should account for when projecting the after-tax return of a long-term hold.
Depreciation is one of the more mathematically distinct calculations in real estate investment modeling, because it produces a deduction without a corresponding cash outlay in the year it is claimed. For an entrepreneur or investor building a Schedule E projection, understanding how the depreciable basis is isolated from land value, and how the recovery period spreads that basis across time, is foundational to modeling the true after-tax cash flow of a rental property. This guide walks through the formula the IRS prescribes for residential rental property, a worked calculation example, and the modeling considerations that typically get overlooked.
Informational calculation reference only. All equations, tools, and outputs on this page are intended strictly for educational modeling and mathematical illustration. They do not constitute certified financial, legal, or tax advice. For specific scenarios, consult a certified public accountant (CPA) or a fiduciary financial advisor.
The Mathematical Formula Behind the Calculation
Under MACRS, residential rental property is assigned a 27.5-year recovery period and depreciated using the straight-line method (as opposed to certain commercial or personal-use assets, which may use accelerated methods). The core formula divides the depreciable basis evenly across the recovery period:
D_{annual} = \frac{B - L}{27.5}
Where $D_{annual}$ is the annual depreciation deduction, $B$ is the total cost basis of the property (purchase price plus qualifying acquisition costs and capital improvements), and $L$ is the allocated value of the land. Land is non-depreciable because, unlike a structure, it is not modeled as a wearing or consumable asset under current tax code.
A second layer of the formula accounts for the mid-month convention, which the IRS applies in both the year a property is placed in service and the year it is disposed of. Rather than allowing a full year of depreciation in the acquisition year, the deduction is prorated as if the property were placed in service at the midpoint of the month of acquisition:
D_{first\ year} = D_{annual} \times \frac{12.5 - M}{12}
Where $M$ is the number of the month the property was placed in service (1 for January, 6 for June, and so on). This adjustment means a property acquired later in the calendar year receives a proportionally smaller first-year deduction, a variable that is frequently omitted from simplified back-of-envelope projections.
Determining the split between $B$ and $L$ is itself a modeling exercise. Common approaches referenced in tax preparation include using the county property tax assessor's land-to-improvement ratio, or commissioning an independent appraisal that separates land and structure value. Depending on the jurisdiction, assessed ratios can vary meaningfully, which is why the land allocation is often treated as the single largest source of variance in a depreciation projection.
Step-by-Step Practical Calculation Example
Consider a single-family rental property modeled with the following inputs:
| Input | Value |
|---|---|
| Total purchase price | $350,000 |
| Closing costs added to basis | $5,000 |
| Total cost basis ($B$) | $355,000 |
| Assessor land allocation (22%) | $78,100 |
| Depreciable basis ($B - L$) | $276,900 |
| Month placed in service | March (Month 3) |
D_{annual} = \frac{276,900}{27.5} = 10,069
Applying the mid-month convention for the first year, with $M = 3$:
D_{first\ year} = 10,069 \times \frac{12.5 - 3}{12} = 10,069 \times 0.7917 \approx 7,972
From year two through year twenty-seven, the model reverts to the full $10,069 annual figure, with a final partial-year adjustment in year twenty-eight to close out the remaining basis. Over the full 27.5-year schedule, the cumulative depreciation deducted equals exactly the depreciable basis of $276,900, assuming no mid-hold disposition or additional capital improvements are layered in.
This calculation is modeled independently of the cash flow, cap rate, and cash-on-cash figures produced by a standard rental analysis, since depreciation is a tax-basis concept rather than an operating metric. An investor projecting after-tax cash flow needs to layer this deduction on top of, not instead of, the operating NOI calculation.
Strategic Applications for Financial Modeling
Depreciation modeling is most frequently applied in a few recurring scenarios. First, when projecting after-tax cash flow, the annual depreciation deduction is applied against net rental income before calculating the investor's marginal tax liability, which can meaningfully shift the after-tax return relative to the pre-tax cash flow figure alone. Second, when an entrepreneur models the sale of a long-held rental property, the cumulative depreciation claimed becomes subject to unrecaptured Section 1250 gain treatment, which is generally taxed at a maximum federal rate of 25% — a materially different rate than standard long-term capital gains brackets, and one that should be modeled as its own line item rather than folded into a blended capital gains assumption.
Third, capital improvements made after the property is placed in service (a new roof, a full HVAC replacement, a room addition) are generally modeled as separate depreciable assets with their own recovery period beginning on the date the improvement is placed in service, rather than being added to the original basis and depreciated over the remaining life of the primary schedule. Financial models that fail to separate these improvement schedules can understate the available deduction in early years.
Finally, for investors holding property through a pass-through entity, depreciation calculated at the property level flows through to the owner's individual return via Schedule E and, depending on participation level, may be subject to passive activity loss limitation rules — a variable that determines whether the deduction can offset other income in the current year or must be carried forward.
A related modeling technique some investors reference is a cost segregation study, which reclassifies certain components of a property (carpeting, certain electrical or plumbing fixtures, landscaping) into shorter recovery periods of 5, 7, or 15 years rather than the full 27.5-year schedule. This front-loads a larger share of the total depreciation into the early years of ownership, which can meaningfully shift a multi-year after-tax cash flow projection even though the total depreciable basis over the life of the asset remains unchanged. Modeling this accurately typically requires an engineering-based study rather than an estimated percentage split, since misclassifying components can create exposure at an eventual audit.
Common Pitfalls and Variable Mistakes
A frequent modeling error is depreciating the full purchase price without excluding land value, which overstates the annual deduction and can create discrepancies during an eventual audit or basis reconciliation. Another common mistake is neglecting the mid-month convention entirely, applying a full year of depreciation in the acquisition year regardless of the actual placed-in-service date, which distorts the first-year after-tax cash flow projection.
Some models also fail to separately track depreciation recapture as the holding period extends, resulting in an inaccurate estimate of net proceeds at eventual sale. Because unrecaptured Section 1250 gain is calculated based on the cumulative depreciation actually claimed (or allowable, even if not claimed), a model that ignores this running total will understate the tax liability due at disposition. Additionally, personal-use days for properties that mix personal and rental use can trigger allocation rules under IRC Section 280A, reducing the depreciable share proportionally — a variable frequently omitted from simplified vacation-rental models.
Another variable worth modeling carefully is what happens when a capital improvement is made mid-hold. Because each qualifying improvement generally starts its own 27.5-year (or shorter, if segregated) recovery schedule from its own placed-in-service date, a spreadsheet model that simply adds the improvement cost to the original basis and recalculates a blended annual figure will misstate the deduction in every year following the improvement. Tracking each addition as its own depreciation sub-schedule, while more work to model, produces a materially more accurate projection over a long holding period.
To model the full financial picture of a rental property — including cap rate, cash-on-cash return, and multi-year cash flow projections alongside a depreciation schedule — use the rental property calculator to layer operating assumptions on top of the depreciation figures illustrated above.
Disclaimer: While we strive for absolute mathematical precision, actual real-world financial outcomes may vary based on institutional fees, localized tax brackets, changes in federal legislation, or fluctuating market indexes.