Tax Planning
Capitalizing Interest for Property Improvements: Final § 1.263A-15 Rule Changes You Need to Know
Starting October 2, 2025, major new IRS rules change how businesses capitalize interest on improvements to designated property—here’s how to prepare.
By NomadicTax Research Team • 6-7 min read • November 16, 2025
## What’s Changing with § 1.263A-15 (Capitalization of Interest)
On October 2, 2025, the IRS finalized new regulations under Treasury Decision (T.D.) 10034, which significantly revise the interest capitalization requirements for improvements that constitute the production of designated property. The changes remove the "associated property rule" and modify both the definition of “**improvement**” and how mid-production purchases are handled. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
Here’s a closer look:
### Key Provisions
- **Removal of the associated property rule** for improvements under § 1.263A-8(d)(3). Taxpayers will no longer group improvements by buildings or tangible personal property into “associated property” for purposes of interest capitalization. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- **Broader definition of improvement** consistent with § 1.263(a)-3. Now includes exceptions, safe harbors, and elections under that section. Improvement excludes ordinary repairs/maintenance under § 1.162-4(a). ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- **New rules for mid-production purchases**: if you purchase a unit of property and further produce it before it’s placed in service, you must capitalize the full purchase price plus additional production costs. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- **Effective & applicability dates**: These rules apply to taxable years beginning *after* October 2, 2025. If you change your method of accounting to align with the revised §§ 1.263A-8(d)(3) and 1.263A-11(e) & (f), IRS Sections 446 and 481 apply (this often means filing Form 3115) to catch up for the income and deductions. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
## Who’s Affected & Why It Matters
- **Businesses making property improvements**—especially real property or tangible personal property improvements—must evaluate whether those improvements now count as "designated property," under the revised definition. That could shift costs from currently deductible repair expense to capitalized, depreciated or amortized assets. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- Organizations that previously relied on the associated property rule to minimize capitalization should reassess their accounting policies. The broadening of what constitutes an improvement may increase capitalization burden. Mid-production purchases rules now require full capitalization of purchase price plus production overhead. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
## Actionable Steps Businesses Should Take Now
1. **Review your fixed asset schedules and improvement definition**: Identify which real or tangible property improvements previously treated as repairs may now be designated property requiring capitalization.
2. **Assess accounting methods**: If your current accounting method isn’t aligned with the new §§ 1.263A-8(d)(3) and 1.263A-11(e)&(f), you’ll need to file Form 3115 and apply Section 481 adjustment.
3. **Update policies and internal controls**: Ensure capital expenditures are classified correctly, especially mid-production purchases. Your capitalization policy likely needs updating.
4. **Train finance and accounting staff**: So they are aware of how to determine "production of designated property," set up capitalization thresholds, and handle mid-production purchases.
## Example Scenario
ABC Manufacturing is renovating its plant building, repairing roofs, installing new HVAC, and adding structural expansion. Under the old rules, the roofing and HVAC might have been treated as repairs (immediately deductible) using associated property rules. Under the new rule, these now may be **improvements that constitute designated property**, meaning costs must be capitalized and interest allocated over production period. Mid-production materials purchased before placing “unit” in service must include full purchase price plus overhead.
If ABC Manufacturing’s fiscal year begins **November 1, 2025**, the new rules **do apply**, since that's after October 2, 2025. ABC needs to calculate a Section 481 adjustment for the effect of changing its accounting method.
## The Bottom Line
This final rule represents one of the more material changes in § 263A interest capitalization requirements in recent years. Businesses need to understand whether improvements trigger capitalization, how to modify capitalization policies, and how to handle method changes. Early planning — ideally before year-end 2025 — will avoid surprises.