Avoided Cost Method Under 263A(f): Production Period and Eligible Debt

The avoided cost method under Section 263A(f) requires you to capitalize interest into the basis of certain long-lived or high-cost property you produce, on the theory that money spent on production could otherwise have paid down debt. In practice, you capitalize all interest on debt traced to the project, then apply a weighted average rate to any production expenditures that exceed that traced debt. The result gets added to the asset’s basis instead of deducted currently, which shifts taxable income into later years and makes accuracy matter.

Does the Rule Apply to You at All

Two gates come before any calculation. Miss either one and the mechanics below are irrelevant.

First, the small business exemption. A taxpayer that meets the Section 448(c) gross receipts test is entirely exempt from the uniform capitalization rules, including interest capitalization. For tax years beginning in 2026, the threshold is $32 million in average annual gross receipts over the prior three years.¹ Tax shelters cannot use this exemption regardless of receipts.²

Second, the property must be “designated property” under Treasury Regulation § 1.263A-8(b). All produced real property qualifies automatically, with no threshold test.³ Tangible personal property qualifies only if it meets one of three tests, applied at the start of production using reasonable estimates:

Class life of 20 years or more under Section 168.
Estimated production period exceeds two years, regardless of cost.
Estimated production period exceeds one year and estimated production costs exceed $1,000,000.

A custom machine estimated at 14 months and $1.2 million triggers capitalization even if it finishes early or under budget.⁴

There’s also a de minimis exception. Property is not designated property if the production period is 90 days or shorter and total production expenditures (excluding land, adjusted basis of assets used in production, and interest itself) do not exceed $1,000,000 divided by the number of days in the production period.³

The thresholds apply per unit of property, defined in Regulation § 1.263A-10 by a functional interdependence test: components are one unit if placing one in service depends on placing the other in service, or if they’re customarily sold together.⁵ Get the unit definition wrong and every subsequent number is wrong.

When the Production Period Starts and Ends

Interest capitalization runs only during the production period, so its boundaries drive the total dollar amount at stake.

For real property, the period begins on the first date any physical production activity occurs. Clearing land, excavating, demolition, and infrastructure work like roads and utilities all count. Planning, design, and permit applications alone do not.⁶

For tangible personal property, the trigger is different. The period starts when accumulated production expenditures, including planning and design costs, reach at least 5 percent of the total estimated expenditures. Physical work need not have begun.⁶

The period ends when the property is placed in service or ready to be held for sale, and all production activities reasonably expected to be performed by the taxpayer or a related person are complete.⁶ A cosmetic punch list won’t extend the period; unfinished functional systems will.

Suspension for Extended Shutdowns

If production activities cease for at least 120 consecutive days, you can suspend capitalization during the gap. Suspension begins with the first measurement period starting after work stops and ends when work restarts.⁷

Not every stoppage counts. Normal adverse weather, scheduled shutdowns, delays from design flaws, waiting for permits, and time for groundfill to settle are treated as circumstances inherent in production, not cessation.⁷ A project idled through a harsh winter in a cold region doesn’t qualify; a project stopped 150 days when financing collapsed likely does. The suspension election is a method of accounting that must be applied consistently to all qualifying units.

Accumulated Production Expenditures: The Base

The interest calculation runs against accumulated production expenditures. These are the cumulative direct and indirect costs required to be capitalized under Section 263A with respect to the unit.⁸

Direct costs like labor and raw materials form the base. Indirect costs add equipment depreciation for machinery used in production, site insurance, and similar overhead. The cost of land underlying a real property project counts, since it represents tied-up capital. Interest capitalized in prior computation periods gets added back in, so the base compounds as the project progresses. Adjusted bases of any assets used in producing the designated property during their period of use are also included.⁸

Measurement Dates

You measure accumulated production expenditures at regular intervals. If your computation period is the full taxable year, measurement dates must occur at least quarterly. Shorter computation periods require at least two measurement dates per period and at least four during the tax year. Dates must be the same for all designated property during a computation period, spaced at equal intervals.⁹

The IRS can require more frequent measurement when quarterly snapshots miss interest that should be capitalized, which tends to arise when spending is concentrated in short bursts. You can change frequency from year to year as spending patterns shift.⁹

The Two-Tier Calculation

With the base measured, the avoided cost method layers interest in two tiers.

Tier One: Traced Debt

The first tier captures interest on debt directly allocable to the production expenditures for the designated property. A construction loan drawn to build a specific warehouse is traced debt. Allocation follows Treasury Regulation § 1.163-8T, which tracks how loan proceeds were actually used.⁹ All interest incurred on traced debt during the production period must be capitalized to that unit. Previously capitalized but unpaid interest on traced debt also flows into accumulated production expenditures on subsequent measurement dates.

Taxpayers can elect not to trace debt to specific units under Regulation § 1.263A-9(d). That simplifies life for businesses running many simultaneous projects but usually produces a different capitalized amount than tracing would.

Tier Two: Excess Expenditures and the Avoided Cost

If accumulated production expenditures exceed traced debt on a measurement date, the difference is excess expenditures. The theory: those excess dollars could have retired other debt, and the interest you would have saved must be capitalized. That saved interest is the “avoided cost.”⁴

You apply a weighted average rate to the excess. That rate equals total interest incurred on nontraced eligible debt during the computation period, divided by the average nontraced debt outstanding across all measurement dates in the period. Traced debt is excluded from both numerator and denominator to prevent double counting.⁹

If you have no nontraced debt during the period, the rate defaults to the highest applicable federal rate under Section 1274(d) in effect during that period.⁹ This blocks a taxpayer from avoiding capitalization by funding production with equity while holding unrelated debt elsewhere.

Total capitalized interest for the unit is traced-debt interest plus the excess-expenditure amount. The statute caps capitalization at interest actually paid or incurred during the production period, so you’ll never capitalize more than you actually owe.⁴

Which Debt Is Eligible

Only “eligible debt” feeds the tier-two rate. Regulation § 1.263A-9(a)(4) starts with a broad definition, any outstanding debt evidenced by a contract, bond, note, or similar instrument, then carves out several categories:¹⁰

Non-interest-bearing debt like accounts payable and accrued liabilities, unless it happens to qualify as traced debt.
Below-market related party debt bearing interest below the applicable federal rate on the date of issuance.
Personal interest and qualified residence interest under Section 163(h)(2).
Debt of a Section 501(a) tax-exempt organization, except interest attributable to an unrelated trade or business.
Reserves and deferred tax liabilities not treated as debt for federal income tax purposes, regardless of financial statement treatment.
Federal, state, and local income tax liabilities, including deferred tax liabilities under Section 453A and look-back method liabilities.

Flow-Through Entities and Contract Production

Two situations change how the calculation is applied.

For partnerships, S corporations, and other flow-through entities, the avoided cost method runs at both levels. First at the entity, then again at the partner or beneficiary level.⁴ A partner holding personal debt may need to capitalize additional interest beyond what the partnership already capitalized. The dual-level requirement is easy to miss in leveraged real estate partnerships.

When property is produced under contract, the taxpayer who hired the contractor is treated as the producer, but only costs the taxpayer actually paid or incurred count toward accumulated production expenditures.² A company hiring a general contractor to build a factory still capitalizes interest on its own debt.

For real property built under contract, the customer’s production period begins when either the customer or contractor first performs physical activity, whichever comes first. The contractor’s own period starts only when the contractor begins physical work.⁶ Both parties may be capitalizing interest at the same time on the same project.

Interest on debt allocable to property used to produce designated property, such as equipment or facilities dedicated to the construction, is also subject to capitalization to the extent it is allocable to the produced property.⁴ A crane bought on credit and used exclusively on one building project generates interest that gets capitalized into that building’s basis.

1
Internal Revenue Service. Rev. Proc. 2025-32
2
Office of the Law Revision Counsel. 26 U.S. Code 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses
3
eCFR. 26 CFR 1.263A-8 – Requirement to Capitalize Interest
4
Office of the Law Revision Counsel. 26 U.S.C. 263A
5
eCFR. 26 CFR 1.263A-10 – Unit of Property
6
GovInfo. 26 CFR 1.263A-12 – Production Period
7
eCFR. 26 CFR 1.263A-12 – Production Period
8
GovInfo. 26 CFR 1.263A-11 – Accumulated Production Expenditures
9
eCFR. 26 CFR 1.263A-9 – The Avoided Cost Method
10
GovInfo. 26 CFR 1.263A-9 – The Avoided Cost Method