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Cost Seg for New Construction: Maximize Tax Benefits from Day One

Building a new property? A cost seg study during construction can unlock even greater tax savings than studies on existing buildings. Here's how to maximize your benefits.

December 22, 20246 min read

If you're building a new commercial or residential rental property, you have a unique opportunity to maximize your cost segregation benefits. A cost seg study on new construction can be more accurate, more comprehensive, and more valuable than studies on existing properties.

Why New Construction Is Ideal for Cost Seg

Better Documentation

New construction projects have detailed records that make cost allocation more accurate:

  • Contractor invoices with itemized costs
  • Architectural plans showing every component
  • Material specifications for all building elements
  • Change orders documenting modifications
This documentation makes it easier to defend your depreciation claims and can result in higher allocations to short-life assets.

Real-Time Integration

When you plan for cost segregation during construction, you can:

  • Track costs by asset category as they occur
  • Ensure proper documentation is maintained
  • Make design decisions that optimize tax benefits
  • Avoid the estimation required for existing buildings

Maximum Accuracy

Studies on existing buildings require engineers to estimate what percentage of costs went to different components. With new construction, you have actual costs for everything.

Timing Your Cost Seg Study

Option 1: During Construction (Recommended)

The optimal approach is to engage a cost segregation specialist before or during construction:

Benefits:
  • Real-time cost tracking by asset category
  • No estimation required—actual costs are used
  • Design modifications can optimize depreciation
  • Report ready when the building is placed in service
When to Start: Ideally during the design phase, but anytime before substantial completion works.

Option 2: At Completion

You can also commission a cost seg study when construction is complete:

Benefits:
  • All costs are finalized
  • Building can be inspected in finished state
  • Still better documentation than existing buildings
Timing: Order the study 1-2 months before the building is placed in service.

Option 3: After Placed in Service

If you missed the earlier windows, you can still do a study after the building is operating:

Benefits:
  • Still get accelerated depreciation going forward
  • Can claim catch-up deduction for first-year benefits missed
Note: The sooner you act, the more benefit you capture.

What Can Be Reclassified in New Construction?

New construction cost seg studies typically identify 25-40% of total costs as short-life property (compared to 15-30% for existing buildings). Here's what commonly qualifies:

Site Work and Land Improvements (15-Year)

  • Grading and excavation (non-structural)
  • Parking lots and driveways
  • Sidewalks and curbs
  • Landscaping and irrigation
  • Retaining walls (non-structural)
  • Fencing and gates
  • Site lighting
  • Stormwater management systems

Building Components (5-Year and 7-Year)

  • Decorative millwork and trim
  • Specialty flooring (carpet, vinyl, decorative tile)
  • Movable partitions
  • Decorative ceiling elements
  • Specialty lighting fixtures
  • Built-in cabinetry (non-structural)
  • Signage (interior and exterior)
  • Window treatments

Building Systems (Partial Allocation)

Portions of major building systems often qualify:

  • Electrical: Dedicated circuits for equipment, decorative lighting
  • Plumbing: Fixtures, decorative elements, process-related plumbing
  • HVAC: Specialized units, supplemental systems

Example: New Construction Cost Seg

Let's look at a new $3 million commercial building:

Without Cost Seg Study:
  • Total depreciable basis: $3,000,000
  • Annual depreciation: $76,923 ($3M ÷ 39 years)
  • Year 1 deduction: $76,923
With Cost Seg Study (35% reclassified):
Asset CategoryAmountYear 1 Depreciation
5-Year Property (15%)$450,000$162,000
15-Year Property (20%)$600,000$148,000
39-Year Building (65%)$1,950,000$50,000
Total$3,000,000$360,000
*Includes 40% bonus depreciation for 2025 Year 1 Tax Savings (at 37% rate):
  • Without cost seg: $28,462
  • With cost seg: $133,200
  • Additional savings: $104,738

Design Considerations That Maximize Benefits

When you plan for cost segregation early, you can make design choices that enhance tax benefits:

Flooring Choices

  • Carpet and removable flooring = 5-year property
  • Decorative tile = potentially 5-year
  • Structural flooring = 39-year

Lighting Design

  • Decorative fixtures = 5-year property
  • Specialty lighting = 5-year property
  • Standard building lighting = 39-year (partially)

Site Design

  • More parking/landscaping = more 15-year property
  • Decorative fencing = 15-year property
  • Outdoor amenities = potentially shorter lives

Interior Finishes

  • Removable partitions vs. permanent walls
  • Built-in vs. freestanding furniture
  • Decorative vs. structural elements

Working with Your Construction Team

To maximize your cost seg benefits on new construction:

1. Inform Your Contractor

Let your general contractor know you'll be doing a cost segregation study. Ask them to:

  • Maintain detailed cost breakdowns
  • Separate invoices by trade/component when possible
  • Document any changes or modifications

2. Coordinate with Your Architect

Your architect can help by:

  • Identifying design elements that qualify for shorter lives
  • Providing detailed specifications
  • Flagging decorative vs. structural components

3. Engage a Cost Seg Specialist Early

A specialist can:

  • Review plans before construction starts
  • Suggest modifications to optimize depreciation
  • Set up cost tracking systems
  • Ensure proper documentation throughout

Common Mistakes to Avoid

Starting Too Late

The earlier you plan for cost segregation, the better your results. Don't wait until the building is finished.

Poor Documentation

Even with new construction, you need to maintain proper records. Ensure your contractor provides detailed, itemized invoices.

Ignoring Land Improvements

Site work often represents 15-25% of total project cost. Make sure your study captures all land improvements.

Not Coordinating with Your CPA

Your tax professional should be involved early to plan for:

  • Optimal timing for placing the building in service
  • Bonus depreciation elections
  • State tax considerations

Getting Started

New construction represents the best opportunity for cost segregation benefits. With proper planning, you can maximize your tax savings from day one of ownership.


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