Most commercial real estate developers still treat tax planning as something you do after the paint dries. That habit quietly kills millions of dollars in cash flow every year because the biggest tax lever on a ground up project is already locked in before you pour the slab.

If you are breaking ground on a $5 million to $50 million project in the next 12 to 24 months, the combination of 100 percent bonus depreciation and a smart **cost segregation for new construction** plan can shift seven figures of deductions into year one. Done right, this turns your construction schedule into a tax strategy document.

Quick Answer: How Cost Segregation Changes New Construction Economics

Cost segregation is an engineering driven study that breaks a building into buckets with shorter tax lives than the standard 39 year (commercial) or 27.5 year (residential) straight line depreciation. For new construction, that means carving out site work, specialty electrical, plumbing, finishes, and other components that qualify as five, seven, or 15 year property under the Modified Accelerated Cost Recovery System described in IRS Publication 946. When those buckets are paired with current Section 168(k) bonus depreciation rules, a developer can often deduct 25 to 40 percent of total construction cost in the first year the building is placed in service.

On a $12 million build, even a conservative 30 percent reclassification can create $3.6 million of immediate depreciation. At a combined federal and state rate of 35 percent, that is $1.26 million of tax deferral the year you open the doors.

How Cost Segregation for New Construction Actually Works

Developers hear the phrase cost segregation all the time, but most have never seen how granular a good study gets on a ground up project. Understanding the moving parts is what lets you bake tax outcomes into your budget.

The Three Big Buckets in a New Building

For tax purposes, new construction typically breaks into three categories:

• Real property Building structure, load bearing walls, roof, primary HVAC, basic plumbing. Generally 39 year property for commercial or 27.5 year for multifamily.
• Land improvements Paving, sidewalks, curbs, exterior lighting, retaining walls, landscaping, some fencing. Usually 15 year property eligible for bonus depreciation.
• Personal property Items not integral to the building structure that support your specific operations specialty lighting, dedicated electrical, equipment pads, certain millwork and finishes. Often five or seven year property, almost always eligible for bonus depreciation.

On a typical Class B office or neighborhood retail project, 20 to 35 percent of total cost falls into the land improvement and personal property buckets when a detailed study is done. Industrial and hospitality projects can run higher because of heavy power, racking, and specialty mechanical systems.

Timing Matters More Than Most Developers Realize

Under current Section 168(k) guidance, property that meets the qualified property definition and is placed in service after January 19, 2025, generally qualifies for 100 percent bonus depreciation. That means if your new building goes operational in 2026, every eligible five, seven, and 15 year component identified by the study can be written off in full in year one if you choose not to opt out of bonus. The timing rules are precise, so your construction start date, placed in service date, and method elections all have to line up on the return.

This is exactly why cost segregation for a new build is not something to order six months after the certificate of occupancy. The design choices you approve now determine how much of the budget lands in five, seven, and 15 year buckets later.

Why Developers Should Design for Tax Lives, Not Just Value Engineering

Every value engineering meeting is really a tax planning meeting, even if nobody in the room says that out loud. When your team shifts $400,000 from generic lighting into higher end, tenant specific fixtures, or upgrades the exterior from bare concrete to decorative hardscape, you are changing the mix between 39 year and shorter lived property.

For example

• $400,000 in generic 39 year assets yields about $10,256 of first year straight line depreciation.
• The same $400,000 properly designed as five year property with 100 percent bonus can produce a $400,000 deduction the first year the building opens.

At a 35 percent combined tax rate, that single design choice swings current year tax by roughly $136,000. Multiply that by dozens of choices across a $20 million construction budget and you see why serious real estate investors treat the tax engineer as part of the design team, not a formality after the fact.

KDA Case Study: Developer Flips a Tax Bill on a $22 Million Build

Consider a California based developer building a $22 million mixed use project with 80 residential units over 15,000 square feet of ground floor retail. The original plan was to book the entire building as 39 year property and move on. On that approach, year one depreciation would have been roughly $564,000, producing about $197,000 of tax shelter at a 35 percent rate.

KDA was brought in during the construction phase to coordinate tax planning services around the project schedule. Working with the project engineer, we identified and documented approximately $7 million of costs that qualified as five, seven, or 15 year property. That included structured parking decks, site lighting, hardscape, specialty electrical feeds for restaurant tenants, and premium finishes in the amenity areas.

Because the building was placed in service in late 2026, the developer qualified for 100 percent bonus depreciation on all of that shorter lived property under Section 168(k). Instead of taking $564,000 of year one depreciation, the return claimed just over $7.5 million. At a 35 percent tax rate, that translated into about $2.6 million of tax deferral the first year. The cost of the engineering based cost segregation study and strategy work came in under $80,000, so the first year cash on cash return on that planning spend was well over 30 times.

Ready to see how we can help you? Explore more success stories on our case studies page to discover proven strategies that have saved our clients thousands in taxes.

Where Cost Segregation Creates the Biggest Wins in New Construction

Not every project yields the same percentage of accelerated depreciation. Some construction types are simply richer in shorter lived components.

Multifamily, Hospitality, and Medical Office

These asset classes tend to generate large buckets of five and seven year property because of unit level finishes and specialized systems. Think about

• Cabinetry, countertops, and built ins in each unit or room.
• Specialty lighting, low voltage wiring, and audio visual infrastructure.
• Dedicated mechanicals for surgery suites or imaging rooms in medical spaces.
• Common area amenities gyms, lounges, coworking, roof decks loaded with finishes and furniture.

For a $30 million multifamily project, it is not uncommon to see 30 to 35 percent of the total cost allocated to five, seven, and 15 year property with a robust study. At current bonus rules, that can mean $9 million to $10.5 million of year one deductions. If your investor group is facing capital gain from other deals in the same year, that timing can be worth millions in combined tax and preferred return dynamics.

Industrial and Manufacturing Builds

Industrial developers have an additional lever. Heavy electrical, specialized plumbing, and dedicated process infrastructure often qualify as personal property. Add in master power panels, bus ducts, equipment foundations, and certain utility connections and you can see 35 to 45 percent of a plant build end up in bonus eligible lives.

Recent guidance under Section 168(n) for qualified production property overlays another opportunity for certain manufacturing facilities. When those rules intersect with a thoughtful cost segregation for new construction, the result is a building that throws off significant deductions in the first operating year, not a slow 39 year drip.

Retail and Mixed Use

With retail and mixed use, the key is understanding which parts of the build support the tenant and which parts are core shell. Exterior signage, canopies, decorative facades, specialized electrical drops, and some demising work can come into shorter lives when properly documented. The shell stays at 39 years, but a skilled study can still scoop out 20 to 25 percent of total cost into faster buckets.

Red Flag Alert: Common Mistakes That Kill New Construction Tax Savings

When the IRS audits real estate projects, they are not impressed by marketing brochures. They look for documentation and logic. Several recurring mistakes show up in cost segregation for new construction, and developers tend to repeat them from project to project.

Treating Cost Segregation as an Afterthought

The most expensive mistake is waiting until after the building is already in service to think about a study. At that point, many of the easiest opportunities are gone because the design decisions are baked in and contractors may not have broken out labor and materials in a way that supports reclassification.

Engaging a tax strategist and cost segregation engineer during design development means they can flag items that should be broken into separate cost codes for tracking. It is a lot easier to defend $1.2 million of site improvements when your general contractor has a dedicated schedule of values for curbs, sidewalks, and lighting instead of a single line called exterior work.

Overreliance on Rules of Thumb

Some firms still sell cost segregation by quoting industry averages “We can probably reclassify 28 percent of your project.” The IRS has made clear in audits and in guidance that boilerplate percentages are not acceptable support. Studies are expected to be engineering based, with clear methodology and tied out to construction documents and actual cost records.

If your current advisor cannot show you the detailed component listing and how it ties back to your contractor invoices and draws, you are carrying audit risk. For more detail on what a defensible study looks like across different property types, see KDA’s broader discussion in our real estate investor cost segregation guide.

Ignoring State Specific Issues

Many developers work across multiple states. California in particular has quirks around conformity to federal bonus depreciation, property tax classification, and local cost tracking. You can have a study that works federally but creates unexpected property tax conversations at the county level if the wrong items are highlighted as personal property.

This information is current as of June 6, 2026. Tax law moves fast. Before you rely on any single example, verify the current rules with the IRS or the California Franchise Tax Board, or work through it with your advisor.

How to Plan Cost Segregation into Your Next Ground Up Deal

Developers who extract the most value do not treat cost segregation as a line item they order from a vendor. They run it like a process.

Step 1 Align the Capital Stack and Tax Profile

Before you spend a dollar on a study, make sure the investor group can actually use the deductions. If your equity is filled with tax exempt entities or foreign investors that do not benefit from accelerated depreciation, you may be shifting value away from the sponsor without realizing it. By contrast, a sponsor with large capital gains and high marginal rates can benefit enormously from front loaded depreciation even if some limited partners are neutral.

This is where a conversation with a firm that understands both real estate and broader premium advisory services pays for itself. The right structure can ensure that the partner bearing most of the tax friction gets most of the depreciation benefit.

Step 2 Coordinate Design, Construction, and Tax Engineering

Once you know who benefits from accelerated deductions, you can start designing for them. That means

• Having your cost segregation engineer review schematic design and flag high impact components.
• Working with the architect and GC to create cost codes that separate potentially reclassifiable items.
• Ensuring change orders preserve or improve the tax profile rather than unknowingly shifting cost back into 39 year property.

In practical terms, this may mean you happily approve a $250,000 upgrade to exterior hardscape if 100 percent of that spend lands in 15 year land improvement buckets eligible for bonus. Through that lens, the after tax cost of the upgrade might be closer to $160,000 once you account for current year deductions.

Step 3 Lock in Documentation While the Project Is Live

Good studies are built on contemporaneous documentation not guesses years later. During the build, make sure your team retains

• Final stamped plans and specifications.
• Contractor schedules of value with separate lines for site work, utilities, specialty systems, and tenant improvements.
• Change orders and pay applications tied to specific scopes of work.
• Photographs during key construction phases to show where systems are located and how they function.

That package becomes the backbone of the cost segregation report and will be what your advisor leans on if the IRS or a state agency ever asks how you arrived at your allocations under the rules in Publication 946 and related guidance.

Will Aggressive Cost Segregation Trigger an Audit?

Developers often worry that pushing depreciation into year one is waving a red flag at the IRS. The reality is more nuanced. The Service has seen cost segregation for decades and has issued multiple audit technique guides discussing how agents should evaluate studies. They are more concerned with sloppy work than with large numbers supported by real analysis.

What the IRS Looks For

Audit files we have seen and discussions with agents suggest they focus on a few key questions

• Does the report clearly explain the engineering methodology used to classify each component
• Can the cost detail be tied back to contractor invoices, pay apps, and the general ledger
• Are the legal distinctions between real property and tangible personal property applied consistently with court cases and guidance
• Is there obvious double counting or inclusion of land cost that should not be depreciated at all

When the answers are yes, the size of the deduction alone is not what triggers adjustments. Weak studies built on round percentage allocations, missing documentation, or clearly misclassified structural items are what generate trouble.

How to Right Size Your Risk

You control your audit profile much more than you think. Working with a firm that lives in this world daily, keeps up with the latest rulings, and understands how agents are trained is one of the simplest risk management moves you can make. If you are concerned about how a large study will read in context with your other returns, experienced advisors can stage deductions over multiple years by selectively applying or opting out of bonus depreciation.

Frequently Asked Questions About Cost Segregation on New Builds

When is the best time to start planning cost segregation for a new construction project

The best time is during design development, before guaranteed maximum price contracts are signed. That is when you have the most flexibility to shift dollars between structural and nonstructural components. If you are already under construction, the next best time is right now while documentation is still fresh and your contractor can easily break out additional detail.

Can I apply cost segregation if my building is already finished and in service

Yes. The IRS allows you to catch up missed depreciation by filing a Form 3115 change in accounting method, often producing a large one time deduction in the year of change. That said, you will always leave some money on the table versus planning the study into the build, and you may not be able to influence design choices retroactively. Early engagement is still the gold standard.

What if my project uses significant tenant improvement allowances

Tenant improvements often contain rich pockets of five and seven year property. The key is to coordinate between owner and tenant advisors so you do not double count or leave deductions stranded. Clear lease language around who owns which improvements and who bears which costs is essential. A coordinated study can align owner and tenant outcomes.

Do I need a study for a smaller ground up project

For projects under roughly $1 million in total cost, the economics of a full blown engineering report are less compelling. Above that level, especially once you cross $3 million to $5 million, the math tends to support a detailed study. The precise breakpoint depends on your tax rate, financing, and hold period. An initial screening conversation with a tax strategist will tell you quickly whether it is worth pursuing.

Will my lender care if I accelerate depreciation

Most commercial lenders underwrite based on cash flow and collateral, not book tax depreciation. Accelerated deductions generally improve after tax cash flow to the ownership group, which can make the deal healthier from the bank’s perspective. You will want to coordinate with your lender about any noncash charges that affect covenant calculations, but in practice, we rarely see lenders object to well supported cost segregation strategies.

Bottom Line

For developers, depreciation is not a boring footnote on page three of the tax return. It is one of the main levers that determines whether a project throws off cash in the early years or quietly starves the sponsor of liquidity. In the current environment, where 100 percent bonus depreciation under Section 168(k) can apply to large portions of a new building, ignoring cost segregation planning is equivalent to ignoring seven figure checks sitting on the job site.

If you are signing construction contracts without a tax strategist at the table, you are playing the game with one eye closed. The combination of engineering based cost segregation for new construction, thoughtful entity planning, and smart investor level structuring can turn the year you place a project in service from a tax problem into a tax asset.

Book Your Real Estate Tax Strategy Session

If you are a developer or real estate investor planning a ground up project in the next 24 months, now is the time to align your design, construction, and tax strategy so you keep more of every dollar you build. Book a focused consultation with KDA and walk away with a clear, project specific roadmap for using cost segregation, bonus depreciation, and entity structure to improve your after tax returns. Click here to book your consultation now.

The IRS is not hiding these deductions you simply were not taught how to design for them.