How to Estimate Land Value for a Cost Segregation Study
Learn how land value affects your depreciable basis, which methods the IRS expects you to support, and how to avoid common allocation mistakes.
TLDR: Land isn't depreciable, only improvements are, so a supportable land value is the foundation of a defensible cost segregation study. Use an appraisal when available, or a documented ratio or comparable-sales approach.
If you own investment real estate, accurately estimating your land value is one of the most important steps in a successful cost segregation study. Get it wrong, especially on the low side, and you could face IRS scrutiny, a reduced depreciation benefit, or an audit of your entire tax return.
In this guide, we break down how land value is determined, why the IRS cares, and the four methods used to arrive at a defensible number.
Why Land Value Matters in Cost Segregation
When you purchase real estate, you are acquiring both the land and the building. Land is not depreciable for tax purposes, only the improvements on the land are. That means before we can calculate your depreciable basis, we must first estimate and subtract the value of the land from your total purchase price.
The IRS requires that any land value used in a cost segregation study be supported by data. The IRS position is that the land value should be determined first and based on its "highest and best use." An accurate, well-documented land value is fundamental to the defensibility of your entire cost segregation study.
Cost Seg Example
| Purchase price for property | $1,000,000 |
| % of purchase price allocated to land (which is non-depreciable) | 20% |
| Depreciable basis | $800,000 |
| % of depreciable basis reclassified into shorter life categories with a cost seg | ≈ 25% |
| Assets eligible for accelerated depreciation with a cost seg | ≈ $200,000 |
| Year 1 tax savings at a 37% income tax rate with a cost seg | ≈ $74,000 |
Higher depreciation → lower taxable income → improved cash flow
Note: Actual results will depend on the specific features of your property (e.g., quality of the property, condition, year of purchase, renovation work, location, etc.).
How the IRS Views Land Value Allocation
Taxpayers must allocate a portion of the purchase price to non-depreciable land, but there is no single "required" method for making this allocation. What the IRS does require is that the method used be reasonable, supportable, and consistent with accepted appraisal principles.
An unsupported or artificially low land value is a red flag. If the IRS identifies an indefensible land value, they may scrutinize other aspects of the cost segregation study or the tax return as a whole. This is why working with an experienced cost segregation professional matters.
Four Methods for Estimating Land Value
1. Appraised Land Value (Best Practice)
The gold standard for determining land value is a formal appraisal performed by a qualified, certified real estate appraiser. If you obtained an appraisal for financing purposes, it may already include the appraiser's opinion of site value. This document should be your first stop when determining the land value.
Most residential appraisals use a standardized format, called a Uniform Residential Appraisal Report (URAR). This report contains a "Cost Approach to Value" section on the third page, which usually has the appraiser's opinion of site value. That figure can be used directly to support the land allocation in your cost segregation study.
See the image below for a typical site value presentation.
If you have an appraisal that assigns a specific site value, that figure takes priority over all other methods.
2. Property Tax Assessment (Ratio Method)
If you don't have a formal appraisal, or if your appraisal doesn't include a site value opinion, then the property tax assessment ratio method is the widely accepted alternative. This method is supported by case law (Nielsen v. Commissioner), which established that a land value may be calculated using a ratio derived from property tax assessment records.
Steps to determine land value using the tax assessment ratio method:
- Find the property tax assessment using a tool like Regrid or your local town/county tax assessor's website.
- Identify the Assessed Land Value and Total Assessed Value within the property tax assessment. Typically, Total Assessed Value = Assessed Land Value + Assessed Improvement Value.
- Calculate the Land %: Assessed Land Value divided by Total Assessed Value.
- Multiply the Land % by the Purchase Price to estimate the Land Value.
- Subtract the Land Value from the Purchase Price to determine the Depreciable Basis.
Example:
- You purchase a property for $1,000,000.
- The tax assessment shows:
- Assessed Land Value: $100,000
- Assessed Improvement Value: $200,000
- Total Assessed Value: $300,000
- Land % = $100,000 / $300,000 = 33.33%
- Land Basis = 33.33% × $1,000,000 = $333,333
- Depreciable basis = $1,000,000 − $333,333 = $666,667
We are happy to assist with this method if you need help. Just contact our team.
3. Vacant Land Comparables
Another frequently used method is identifying comparable vacant land sales in the area. This approach mirrors how an appraiser estimates site value: by finding recent sales of unimproved land with similar characteristics (size, location, zoning) and comparing them to the subject property.
This is an abbreviated version of a formal appraisal and can be performed by the taxpayer. The key is that comparables must be genuinely similar and the reasoning well-documented.
4. Rule of Thumb — Not Recommended
A common but problematic approach is the "rule of thumb," where CPAs or taxpayers simply allocate 10%, 15%, or 20% of the purchase price to land without any supporting data. While this method is widely used, we strongly advise against it.
Without supporting documentation, a rule-of-thumb land value is unlikely to withstand IRS scrutiny and leaves your cost segregation study, and your whole tax return, exposed.
Video Walkthrough and Spreadsheet to Calculate Land Value
Summary: How We Determine Land Value
As cost segregation professionals, our role is to advise clients on the appropriate methods and communicate the risks associated with using an unsupported land value. The responsibility for ultimately determining the land value rests with the taxpayer, but we are here to guide that process.
We typically rely on county property tax assessment values when preparing initial cost segregation estimates. However, if you have an appraisal with a different site value, we will use that instead. As part of engaging us to create your cost segregation study, we work with you to determine the most accurate and defensible land value possible.