County-assessor values and professional appraisals can both inform land allocation, but they do not answer every valuation question equally. Start with the evidence supporting relative land and building values at acquisition, not whichever method produces the largest deduction.

An assessment can provide separate land and improvement figures. An appraisal needs the right scope, valuation date, and explanation to support your allocation. Neither document’s label resolves those questions by itself.

Key Takeaways

• Federal depreciation allocation looks to the relative values of depreciable property and the whole property at acquisition.
• IRS guidance permits assessed-value allocation when you are uncertain of land and building fair market values.
• An assessment percentage is not the same thing as the assessor’s dollar amount or your federal tax basis.
• Check whether an appraisal actually supports separate land and building values for the relevant acquisition date.
• Reconcile conflicting evidence with your tax advisor instead of automatically choosing the lower land percentage.
• Keep the evidence and allocation calculation together with your acquisition records.

Can you use county-assessor values to allocate land and building cost?

Yes. IRS guidance allows allocation using assessed land and building values when you are uncertain of their fair market values.

IRS Publication 551 describes allocating a lump-sum purchase using each asset’s fair market value relative to the whole property. It then permits assessed-value allocation when land and building fair market values are uncertain.

That is conditional guidance, not a statement that every county ratio is appropriate for every purchase. Check that the parcel, buildings, and valuation figures match the property you acquired.

For an assessment-based calculation, divide assessed land value by combined assessed land and improvement values. Apply that percentage to the appropriate acquisition cost. Do not subtract the assessor’s land dollar amount directly from a different purchase price.

Our land-value allocation guide explains the underlying calculation. For the labels on an assessment, see improvement value on a property tax bill.

When should you consider an appraisal instead?

Consider an appraisal when existing records do not adequately support the acquisition-date land and building values you need to allocate cost.

The relevant federal regulation, Treasury Regulation Section 1.167(a)-5, bases depreciation allocation on relative values at acquisition. That makes the valuation date and the property covered important review questions.

Ask whether your existing appraisal contains a supported land/building allocation. A total-property conclusion alone does not supply the separate values needed for that calculation.

If you commission additional work, ask the appraiser and your tax advisor to agree on its purpose and scope. Request an explanation of the valuation date, property interest, land conclusion, building conclusion, and supporting evidence.

Compare the evidence, not just the percentage

This is a review checklist, not an IRS ranking of valuation methods. It does not establish a universal land percentage, appraisal price, or mandatory report-age cutoff.

What should you do when the assessment and appraisal disagree?

Document the difference and ask your tax advisor to evaluate the evidence before selecting the allocation used on your return.

Start with dates and scope. Do both documents cover the same parcel, buildings, condition, and property interest? Does either figure reflect a different valuation date or purpose?

Then compare the underlying values and explanation. Do not assume an appraisal must reduce land value, or that a larger building allocation proves greater accuracy.

Illustration only: Assume a $900,000 rental purchase with no closing costs or other basis adjustments. Its assessment lists $180,000 of land and $420,000 of improvements.

The assessment-based land percentage is $180,000 ÷ $600,000 = 30%. Applied to the purchase price, that produces $270,000 of land basis and $630,000 of remaining acquisition basis.

Suppose an acquisition-date appraisal instead supports a 25% land allocation after professional review. That would produce $225,000 of land basis and $675,000 of remaining acquisition basis.

The second outcome is not a recommendation to select 25%. These are hypothetical inputs, not typical percentages or evidence about your property. An appraisal could support more land rather than less.

The $45,000 difference is basis, not an immediate deduction or tax refund. Depreciation also depends on asset classification, service dates, methods, conventions, and elections.

How does a supported allocation affect first-year depreciation?

A supported allocation establishes how much acquisition basis remains outside nondepreciable land before depreciation is calculated for qualifying assets.

IRS Publication 527 explains that land cannot be depreciated. It also distinguishes basis from a current deduction and describes rental-property depreciation rules.

Continue only the hypothetical 25% land scenario, assuming your advisor accepts its supporting evidence. Of the $675,000 remaining basis, assume a properly supported asset analysis assigns:

• $75,000 to qualifying 5-year rental appliances and furniture.
• $45,000 to qualifying 15-year land improvements.
• $555,000 to a residential rental building.

These illustrative classifications and amounts are not a component-level DIY allocation method or a promised study result.

Assume a full calendar tax year, March service dates, and assets remaining in service through year-end. Use GDS, with no ADS requirement or Section 179 deduction. Assume the half-year convention applies to short-life assets and the mid-quarter convention does not apply.

To isolate regular MACRS, assume a valid election out of bonus depreciation for each relevant short-life class. IRS Notice 2026-11, Section 2.05 describes the class-by-class election. This assumption is not a recommendation to elect out.

IRS Publication 946 provides the applicable recovery periods and percentage tables. Table A-1 supplies the short-life rates below. Table A-6 supplies the March residential-building rate under the mid-month convention.

At an assumed 37% federal marginal rate, $33,228.45 × 37% = $12,294.53 of potential federal tax reduction, rounded to cents. Assume the entire deduction is usable currently. State taxes and other tax interactions are excluded.

This is the tax value of total illustrated depreciation, not an appraisal’s incremental benefit or the incremental benefit of cost segregation.

At-risk and passive activity rules can limit current loss deductions, as explained in IRS Publication 925. A sale can also trigger depreciation recapture consequences under the rules described in IRS Publication 544.

What documentation should you keep?

Keep the source values, acquisition records, allocation calculation, and explanation supporting the allocation you actually use.

Use this practical handoff checklist with your CPA and study preparer:

1. Purchase agreement and closing statement identifying the property and acquisition cost.
2. Parcel records showing land and improvement figures, valuation date, and source.
3. Any appraisal used, including its effective date, scope, assumptions, and supported allocation.
4. A calculation reconciling the allocation percentages to acquisition basis.
5. An explanation of material differences between the assessment and other valuation evidence.
6. The final asset-classification and depreciation records, including applicable elections.

This checklist is a preparation aid, not a claim that every item is universally required in this exact form. Acquisition-cost adjustments and financing costs also need separate classification.

A professional cost segregation study addresses asset classification after the appropriate starting basis is established. Do not use the possibility of accelerated deductions to justify an unsupported land allocation.

Frequently Asked Questions

Choose an allocation based on supportable acquisition-date values, not the size of the projected deduction.

Does the IRS require an appraisal for every land allocation?

Publication 551 permits assessed-value allocation when you are uncertain of land and building fair market values. An appraisal is not the only allocation evidence described in that guidance.

Can I use an appraisal prepared for my lender?

Check its scope, effective valuation date, and whether it supports separate land and building values. Do not assume a total-property valuation alone establishes the allocation for your return.

Is a lower land allocation automatically better?

No. A lower land percentage leaves more basis outside land, but the allocation still needs support. Tax consequences do not establish valuation accuracy.

Is there a standard land percentage for every rental property?

The cited allocation guidance uses relative values, not a universal percentage. Determine the appropriate allocation from evidence relevant to the property and acquisition.

Make the allocation supportable before accelerating depreciation

A useful valuation record explains what was valued, when it was valued, and how the land/building split was supported. Resolve that starting point before estimating depreciation benefits.

Request a free proposal from R.E. Cost Seg to discuss your property and study documentation.

Confirm your allocation, asset classifications, and deduction eligibility with your tax advisor before filing.

‍