Improvement value on a property tax bill generally means the assessor’s value assigned to buildings and other improvements, separately from the land. It does not automatically equal the amount you can depreciate on your federal tax return.
That distinction matters when you buy a rental property. Your assessment may help establish an allocation percentage, but federal depreciation starts with the appropriate tax basis. The assessor’s dollar figure is not a substitute for that calculation.
Key takeaways
- Assessed improvement value and federal depreciable basis serve different purposes.
- Do not confuse an assessor’s “improvements” category with the federal tax category “land improvements.”
- Allocate a purchased property’s cost using relative fair market values at acquisition.
- IRS guidance permits assessed-value allocation when you are uncertain of the land and building fair market values.
- Land itself is not depreciable. Qualifying buildings and shorter-life assets follow different depreciation schedules.
- Loan-origination costs are not automatically part of building basis.
What is improvement value on a property tax bill?
Improvement value is the assessor’s assigned value for buildings and other improvements, distinguished from the value of the underlying land.
The Santa Clara County Assessor’s glossary, for example, defines improvements as buildings or structures generally attached to land. Its definition can also include certain business fixtures. This is a local definition, not a uniform national classification rule.
An existing building can have improvement value even if you have not renovated it recently. The label identifies a valuation category, not just money spent on upgrades during the current year.
Read the labels before doing the math
Your assessment notice or parcel record may distinguish land, improvements, total assessed value, exemptions, and taxable value. Ask your assessor which figures represent the land and improvement components of the same valuation.
Do not assume “assessed value” always means current market value. In New York City’s assessment terminology, assessed value begins with market value multiplied by a level of assessment. Caps can modify assessments for certain classes. Its taxable value also reflects exemptions and, where applicable, transitional assessment rules.
These local differences are why the labels on your own parcel record matter.
| Term | What it describes | What it does not establish by itself |
|---|---|---|
| Assessed land value | The assessor’s value assigned to land | Your federal tax basis in land |
| Assessed improvement value | The assessor’s value assigned to improvements under local rules | A federal depreciation deduction |
| Total assessed value | The property’s assessed valuation under local rules | Necessarily its current market value or purchase price |
| Taxable value | The value used to calculate local tax after applicable adjustments | A substitute for comparable land and improvement valuation figures |
| Federal depreciable basis | The tax basis attributable to qualifying depreciable property | The same dollar amount as assessed improvement value |
| Federal land-improvement classification | The tax classification of particular qualifying site assets | Every asset included in an assessor’s improvements category |
For the underlying land question, see our explanation of land value in cost segregation.
How do you use assessed improvement value to allocate purchase price?
Calculate an assessment-based improvement percentage by dividing assessed improvement value by the combined assessed land and improvement values.
Keep this percentage separate from your tax-basis calculation. First determine whether the assessment is an appropriate allocation reference for your acquisition.
IRS Publication 551 explains that a lump-sum purchase is allocated among assets using their relative fair market values at purchase. If you are uncertain of land and building fair market values, it permits allocation based on their assessed values for real estate taxes.
That conditional guidance is not blanket IRS approval of every county ratio. Keep the parcel record, acquisition documents, and any appraisal supporting your allocation. Ask your CPA to resolve a materially different appraisal or an assessment that does not reflect the property purchased.
Apply the ratio, not the assessor’s dollar amount
Assume you buy a residential rental property for $600,000. Its assessment separately lists $80,000 of land and $320,000 of improvements.
Assume these comparable assessment figures are an appropriate allocation reference. For simplicity, exclude closing costs and other basis adjustments.
- Combined assessed value: $80,000 + $320,000 = $400,000.
- Land percentage: $80,000 ÷ $400,000 = 20%.
- Improvement percentage: $320,000 ÷ $400,000 = 80%.
- Land acquisition basis: $600,000 × 20% = $120,000.
- Remaining acquisition basis: $600,000 × 80% = $480,000.
The $320,000 assessment figure is not the federal building basis. The $80,000 assessed land value is not the amount to subtract directly from the $600,000 purchase price.
Use land and improvement figures from the same assessment and valuation basis. Do not combine a gross improvement value with a total reduced by exemptions. If the labels are unclear, ask the assessor before calculating a ratio.
If the assessment and other valuation evidence disagree, see county assessor vs. appraisal for land allocation. That guide covers method selection and documentation, rather than the meaning of the improvement-value label.
Which acquisition costs belong in basis?
Publication 551 distinguishes costs of buying property from costs of obtaining a loan. Eligible acquisition costs can increase property basis. Mortgage-origination fees incurred to obtain financing do not increase building basis. Generally, those loan costs are recovered over the loan term.
Have your CPA classify closing-statement charges by purpose rather than adding every fee to improvements. Construction capitalization requires a separate review.
Is improvement value depreciable under MACRS?
Federal depreciation applies to qualifying tax basis, not to the improvement-value number printed on your tax bill.
IRS Publication 527 explains that land cannot be depreciated. It also describes rental depreciation basis, land/building allocation, and limits on rental losses.
That means the $480,000 in the example is an allocation starting point. It is not a first-year deduction. Its treatment depends on the assets acquired, their classification, and when they enter rental service.
Improvement value vs. land improvements
An assessor’s improvement value and the federal classification of land improvements answer different questions. The first describes a local valuation category. The second concerns the tax treatment of particular assets.
A building can appear in an assessor’s improvements category without becoming 15-year land-improvement property. Do not apply one recovery period to the entire assessed improvement amount.
Under GDS, residential rental buildings generally have a 27.5-year recovery period. Nonresidential buildings generally use 39 years. Qualifying shorter-life assets can follow different schedules.
IRS Publication 946 lists these recovery periods and provides the MACRS percentage tables. Its asset class 00.3 includes qualifying depreciable land improvements with 15-year GDS and 20-year ADS recovery periods.
Examples can include fences, sidewalks, and certain drainage facilities. Classification depends on the asset and its use. The class excludes buildings, structural components, and improvements assigned to other classes.
Do not classify every landscaping or site-preparation cost as 15-year property. Publication 527 says clearing, grading, planting, and landscaping costs are usually part of nondepreciable land. Certain costs closely associated with depreciable property can qualify for different treatment.
An assessor’s “improvements” line therefore does not tell you which assets qualify for 5-year, 15-year, or building depreciation. Our guide to asset recovery periods explains that separate classification step.
What if you convert your home to a rental?
Do not apply the purchase example unchanged to a former personal residence. Publication 527 generally uses the lower of adjusted basis or fair market value at conversion for depreciation, excluding land.
Have your CPA establish the correct starting basis before allocating depreciation.
How does the allocation affect your first-year deduction?
The allocation determines how much acquisition basis belongs to nondepreciable land before you calculate depreciation for the remaining assets.
Continue the hypothetical $600,000 rental purchase. Assume a properly supported asset analysis assigns the $480,000 remaining basis as follows:
- $60,000 to qualifying 5-year rental appliances and furniture.
- $40,000 to qualifying 15-year land improvements.
- $380,000 to the residential rental building.
These are illustrative allocations, not promised study results or a recommended percentage for every property.
Assume a full calendar tax year. All assets enter service in March and remain in service through year-end. The example uses GDS and the half-year convention for short-life assets. Assume the mid-quarter convention does not apply, no ADS requirement applies, and no Section 179 deduction is claimed.
To show regular MACRS, assume a valid election out of bonus depreciation for each relevant short-life class. IRS Notice 2026-11 describes the class-by-class election under Section 168(k)(7). Ask your CPA whether that election suits your circumstances.
| Asset | Allocated basis | First-year table rate | First-year depreciation |
|---|---|---|---|
| Qualifying 5-year assets | $60,000 | 20.00%, Table A-1 | $12,000.00 |
| Qualifying 15-year assets | $40,000 | 5.00%, Table A-1 | $2,000.00 |
| Residential rental building, March service date | $380,000 | 2.879%, Table A-6 | $10,940.20 |
| Total depreciable assets | $480,000 | Different rates apply | $24,940.20 |
| Nondepreciable land | $120,000 | Not depreciable | $0 |
The building uses the mid-month convention, not the half-year convention. These calculations use the published table percentages, including their rounding.
At an assumed 37% federal marginal tax rate, $24,940.20 × 37% = $9,227.87 of potential federal tax reduction. This assumes the entire deduction is usable currently and excludes state taxes and other tax interactions.
This is the tax value of total illustrated depreciation, not the incremental benefit of cost segregation.
A deduction is not a guaranteed refund. At-risk and passive activity loss limits can delay the benefit. A sale can also produce depreciation recapture consequences, as explained in IRS Publication 544.
For an initial estimate rather than a final tax calculation, try our real estate depreciation calculator.
Frequently asked questions
Assessed improvement value is not federal depreciable basis, and land itself is not depreciable.
What does improvement value mean on a property tax bill?
Improvement value generally means the assessor’s value assigned to buildings and other improvements, separately from land. Check your assessor’s definitions because local rules vary.
Is assessed improvement value the same as depreciable basis?
No. Assessed improvement value serves local property-tax purposes. Federal depreciation generally starts with your allocated acquisition cost, subject to basis adjustments and eligibility rules.
Can I use my property tax assessment to allocate land and building cost?
IRS guidance allows allocation based on assessed values when you are uncertain of the land and building fair market values. Apply the resulting percentages to your acquisition basis, rather than substituting the assessment’s dollar amounts.
What is the difference between improvement value and land improvements?
Improvement value is an assessor’s valuation category. Land improvements are particular site assets whose federal depreciation treatment depends on their classification. The labels are not interchangeable.
Are land improvements depreciable?
Qualifying land improvements with a determinable useful life can be depreciable. Many fall within the 15-year GDS class, but land itself is not depreciable.
Put the right value into the right calculation
Use the assessment to understand the land/improvement split, then establish the correct tax basis and asset classifications. Do not depreciate the assessor’s figure without that reconciliation.
Request a free proposal from R.E. Cost Seg to discuss your property and the documentation a study would need.
Confirm your allocation, depreciation method, and deduction eligibility with your tax advisor before filing.
