Entity Setup
Navigating the New Interest Capitalization Rules for Designated Property Improvements
Final regulations under section 263A amend how businesses capitalize improvements—understand what qualifies as “designated property” and how these changes affect your accounting methods.
By NomadicTax Research Team • 5-8 min read • November 21, 2025
## Background: What Triggered These Final Regulations
The IRS published **TD 10034** in Internal Revenue Bulletin 2025-43, finalizing regulatory changes under IRC § 263A(f) concerning interest capitalization on improvements that are designated property. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
Major changes include:
- Removal of the **associated property rule** and similar rules in § 1.263A-11(e). ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- Clarification and tightening of the definition of “improvement” for purposes of designating property under § 1.263A-8(d)(3), aligning it with § 1.263(a)-3. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
## Who Is Affected
- Businesses that purchase or construct **designated property**—real or tangible personal property subject to production or development. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- Those with **gross receipts over $25 million** (adjusted for inflation) are subject to these capitalization rules. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- Companies with improvements made before placing property in service, or making capital investments that previously avoided associated property rules, will need to revisit their approach.
## What Changes You Need to Know
| Before | After (post-Oct 2, 2025) |
|--------|--------------------------|
| Associated property rule allowed grouping certain improvements to reduce capitalization of interest costs. | That rule is removed—interest must be capitalized without that grouping exception. |
| Definition of “improvement” more broadly interpreted. | Now defined more narrowly, consistent with § 1.263(a)-3, including specific exceptions and safe harbors. |
## Accounting & Compliance Implications
- **Change in method of accounting**: Entities affected must file **Form 3115** to switch to the new method. ([irs.gov](https://www.irs.gov/irb/2025-43_IRB?utm_source=openai))
- Potential increased **interest capitalization**, which increases basis and reduces current deductions—may impact cash flow and tax planning.
- Need to review ongoing capital projects and improvement expenses now to anticipate when placed in service dates will bring new rules.
## Practical Examples
- **Manufacturing firm** expanding its plant: removal of associated property rule means every improvement (roof, windows, wiring, etc.) must be evaluated individually for interest capitalization rather than grouped.
- **Real estate developer** renovating multiple units: stricter “improvement” definition may exclude certain repairs previously treated favorably; classification of component parts matters more.
## Tips to Adapt Smoothly
- Conduct an inventory of properties/improvements in progress—note their starting dates and costs.
- Update internal policies for capital expenditure reviews—define what qualifies as “improvement” under § 1.263(a)-3.
- Consult with your tax or accounting firm early to file needed elections and adjustments (Form 3115) before deadlines.
- Model the impact: simulate how removing associated property rule changes interest capitalization, basis, depreciation schedules.
With these final rules now in effect (from October 2, 2025), businesses need to respond proactively to avoid surprises and optimize their capital investment strategies under the updated section 263A regulations.