The Opportunity Zone substantial improvement test generally requires additions to a used property’s adjusted basis to exceed 100% of that basis during a 30-month period. For property located in a Qualified Opportunity Zone comprised entirely of a rural area, the threshold is 50% for determinations made on or after July 4, 2025. Land basis is generally excluded when the acquired property includes a building, making the purchase-price allocation and improvement ledger central to the calculation.
This is a property qualification test, not a measure of whether the project is economically sound. A project can satisfy the tax rule and still fail because of construction cost, leasing, financing, entitlement, or market risk.
When Does the Opportunity Zone Substantial Improvement Test Apply?
Owned tangible property generally must satisfy either the original-use requirement or the substantial-improvement requirement to qualify as Qualified Opportunity Zone business property. The substantial-improvement route is most relevant when a Qualified Opportunity Fund or Qualified Opportunity Zone business purchases a building or other tangible property that was previously placed in service in the zone.
Original use begins when property is first placed in service in the QOZ for depreciation or amortization purposes. Used property brought into a zone may satisfy original use if it was not previously placed in service there. Vacant real property can also qualify under specified one-year or three-year vacancy rules. The IRS Opportunity Zone frequently asked questions summarizes these distinctions, while the controlling requirements appear in 26 CFR 1.1400Z2(d)-2.
The first diligence question is therefore not “how much must we spend?” It is “which property must satisfy which qualification route?” Applying the improvement test automatically can overstate required capital when original use is available. Assuming original use without evidence can create a qualification failure.
How to Calculate the Opportunity Zone Substantial Improvement Test
1. Confirm the tract and the applicable threshold
Verify the property’s census tract and QOZ designation from an authoritative source. Then determine whether the QOZ is comprised entirely of a rural area under the current rule. IRS Notice 2025-50 identifies 3,309 existing QOZs treated as entirely rural and explains the reduced threshold.
For a general QOZ, additions to basis during the selected 30-month period must exceed 100% of adjusted basis at the beginning of that period. For property in an entirely rural QOZ, additions must exceed 50%. “Exceed” matters. Spending exactly $5 million against a $5 million tested basis does not exceed 100%.
2. Separate land from the building
When a building and its underlying land are purchased together, substantial improvement of the building is measured against the building’s adjusted basis. The land generally does not need to be separately substantially improved. Revenue Ruling 2018-29 established this treatment, and the final regulations preserve it.
The allocation cannot be treated as a plug chosen to produce a lower threshold. The purchase agreement, appraisal, tax records, cost-segregation work, and financial reporting should be reconciled. A defensible allocation should reflect the transaction facts and applicable tax rules.
3. Establish adjusted basis at the start of the period
The denominator is adjusted basis at the beginning of the 30-month substantial-improvement period, not necessarily the headline purchase price. Acquisition allocations, capitalized costs, depreciation, and other tax-basis adjustments may affect the amount. Transaction-specific tax advice is necessary because the correct basis depends on the facts and timing.
Consider a hypothetical acquisition with an $8 million price allocated as $3 million to land and $5 million to the existing building. Assume, solely for illustration, that the building’s adjusted basis remains $5 million when the improvement period begins:
General QOZ threshold: additions must exceed $5,000,000.
Entirely rural QOZ threshold: additions must exceed $2,500,000.
A $5 million building program would be insufficient under the general test because the statute requires additions greater than 100%, not equal to it. A prudent budget would include headroom above the legal threshold, but the amount of that headroom is a project decision rather than a statutory percentage.
4. Define which expenditures count
Track expenditures that are properly added to the tested property’s basis. The regulations permit certain original-use assets that improve the functionality of a non-original-use property to be included when the eligible entity elects the prescribed treatment. They do not allow unrelated improvements to be moved into the calculation merely because the properties are nearby.
For example, the regulations describe a hotel whose furniture, exercise equipment, and restaurant equipment may be included when they improve the hotel’s functionality under the applicable election. Improvements to a separate apartment building one block away cannot be counted toward the hotel’s test.
Owners and sponsors evaluating a QOZ rehabilitation can bring the basis allocation, tract evidence, scope, schedule, and capitalization plan to Primior for an initial project assessment before construction commitments become difficult to change.
5. Control the 30-month clock
The test uses a 30-month period beginning after acquisition. The project schedule should identify the selected start, measurement end, committed scope, procurement lead times, permitting dependencies, invoice controls, and evidence that costs were placed in the correct basis account.
Property undergoing improvement can be treated as satisfying the relevant property requirement during the 30-month period if the eligible entity reasonably expects to complete the substantial improvement and use the property in its QOZ trade or business by the end of the period. That reasonable expectation should be supported by more than a high-level construction budget.
The 30-month improvement test is separate from the working-capital safe harbor, which can protect qualifying working capital for up to 31 months under a written designation and spending schedule. Primior’s Opportunity Zone working-capital framework explains that separate execution rule. Similar durations do not make the tests interchangeable.
Can Multiple Buildings Be Aggregated?
The regulations permit aggregation in defined circumstances, but not across any group of assets a sponsor chooses. Buildings may be treated as a single property when they meet parcel, geographic, ownership, and operational requirements stated in the regulations. Buildings on one deed may qualify as a group. Other groupings require conditions such as location in the same or contiguous QOZs and shared business characteristics.
Aggregation can change both the denominator and the eligible improvement pool. The decision should be made before relying on a combined calculation and documented consistently across the model, construction accounting, tax workpapers, and QOF reporting. It should not be used after the fact to offset an under-improved asset with unrelated spending.
Land Is Excluded From the Building Test, Not From Project Risk
The land rule prevents the purchase price of underlying land from inflating the building-improvement denominator. It does not create a passive land-banking exception. The regulations state that unimproved or minimally improved land may fail to qualify when purchased with an expectation that it will not be improved by more than an insubstantial amount within 30 months.
Grading, clearing, contamination remediation, and related property that facilitates active business use may be relevant, depending on the facts. Sponsors should connect the land to an active trade or business, document the intended improvements, and avoid treating tract location alone as sufficient qualification.
Build a Property-Level Compliance Ledger
A usable substantial-improvement ledger should show the acquired property, land and building allocation, beginning adjusted basis, applicable 100% or 50% threshold, 30-month dates, qualifying additions by invoice, excluded costs, cumulative progress, forecast completion, and responsible reviewer. Monthly reporting should reconcile the ledger to the general ledger and construction draw records.
The improvement ledger should also connect to the fund’s broader compliance process. A QOF generally tests whether at least 90% of its assets are QOZ property on two annual testing dates. Primior’s QOF reporting requirements guide explains the records needed for Form 8996, Form 8997, investor basis, and property qualification.
Late-2026 acquisitions need another layer of review. IRS Notice 2026-40 provides transitional guidance as the original designation framework moves toward the program’s new recurring structure after December 31, 2026. Acquisition date, tract status, and applicable start date should be verified rather than assumed.
The Tax Threshold Is Only One Capital Gate
The Opportunity Zone substantial improvement test answers whether sufficient qualifying basis was added within the required period. It does not establish construction feasibility, stabilized value, debt capacity, market demand, liquidity, or an appropriate investment price.
A disciplined approval should run two tests in parallel. The compliance model asks whether the property can qualify and how that conclusion will be evidenced. The investment model asks whether the completed asset can support its total basis under realistic operating, financing, and exit assumptions. Lowering the rural threshold from 100% to 50% may reduce the minimum qualifying spend, but it does not turn a weak rehabilitation plan into a sound investment.
Investors, owners, and sponsors assessing a QOZ property can work with Primior to evaluate the project basis, improvement plan, capitalization, development controls, and long-term operating case alongside independent legal, tax, accounting, appraisal, engineering, and other professional advisers.
This article is provided for general informational purposes only and does not constitute investment, legal, tax, accounting, appraisal, engineering, or other professional advice, an offer to sell, or a solicitation of an offer to buy any security or investment product. Opportunity Zone qualification depends on the property, entity structure, acquisition date, tract designation, use, expenditures, records, and applicable law. All investments involve risk, including possible loss of principal.
