Bjorn Swanson

Cost segregation can pull years of depreciation forward into one tax year. Here is when it pays, when it does not, and how to do it right. 

Most property owners depreciate a building the slow way. You buy a rental, a shop, or a piece of ground with improvements on it, and the whole works gets spread over 27.5 or 39 years. That is the default. For a lot of owners it also leaves money sitting on the table. 

Cost segregation is one way to find out whether some of that basis belongs in a faster lane. It is an engineering-based study that separates the parts of a property that wear out quickly from the long-life shell. Certain components, like some flooring, cabinetry, dedicated wiring, paving, and fencing, can move to shorter schedules depending on how they are built and used. Reclassify them and you depreciate them much faster. 

Here is why it matters more right now. The 2025 tax law brought back 100% bonus depreciation and made it permanent for qualifying property acquired and placed in service after January 19, 2025. Property with a recovery period of 20 years or less can qualify. So a large share of what a study moves into the shorter classes can be written off in the first year, subject to the usual limits. That is a real change from the phase-down that had bonus depreciation headed toward zero. 

Now the part I want to be straight about. Cost segregation does not create new deductions. It moves them forward. You recover the same basis, just faster, and it can change how some of the property is taxed when you eventually sell. For an owner who can actually use the deduction and plans to hold the property, that trade is usually worth making. For some owners it is not. Knowing which one you are is the whole game. 

First, a quick gut check 

A study costs real money, and it earns its keep only in the right situation. Four questions decide most of it: 

• Is the depreciable basis substantial? Land does not count, and a small building rarely justifies the cost. 

• Can you actually use the deduction this year or soon? A deduction you cannot use for years is worth less, sometimes a lot less, than one you can use now. 

• Will you hold the property several years? The benefit is present value. Sell too soon and recapture can claw a lot of it back. 

• Does the projected benefit clearly beat the study and filing cost? 

  
  

If the first three are yes, the fourth is worth running the numbers on. That is the part we handle. 

Lane one: buildings you own or are buying 

If you are a landlord or a business owner with a commercial or residential building, this is the familiar case, and it splits two ways. 

A newly purchased or newly built property is the clean scenario. The study carves out the short-life components, and under today's rules much of that can come off in the first year you place it in service. On a purchase, the study works on the building basis after you back out land, not the full price. How much reclassifies depends heavily on the property type. A medical building, a restaurant, or a manufacturing space usually yields more than a plain warehouse or a basic apartment building. 

A property you have owned for years can still be studied, but read this next part carefully, because it is where people get the wrong idea. A look-back study does not give you today's 100% rate on an old building. The bonus piece is set by the rules in place when the asset was acquired and placed in service, including the rate then in effect. You claim the cumulative catch-up in the current year through an accounting method change on Form 3115, generally without amending prior returns. As a rough guide, that rate was generally 100% for most property placed in service from 2018 through 2022, 80% in 2023, 60% in 2024, and 40% or 100% for 2025 depending on the January 19 line. So a building you bought in that 2018 to 2022 window can throw off a genuinely large catch-up. Buy it in 2024 and the number is smaller. Either way the deduction is real, but its size depends on the year the property went into service, not on when you run the study. 

One caution on the method change: whether it is available depends on your facts, including your current method and whether the depreciation was allowable but not taken. It is usually available, not always. 

Where the deduction actually lands 

This is the point most articles skip, and it is the one that trips up business owners. A cost segregation deduction attaches to the property, and whether it offsets your other income depends on how you hold it. 

If you own a building personally and rent it to your own operating company, that is a self-rental, and the rules are not intuitive. Net rental income from a self-rental is treated as active, but a rental loss, which is exactly what a big first-year deduction can create, generally stays passive. It may not offset the income from your business the way you would expect. There is sometimes a fix. When the rental and the business are commonly owned and meet the requirements, they may be grouped as a single activity, which can free the loss up. But it has to qualify, it may need to be disclosed, and it binds future years, so it gets decided before the return is filed, not after. 

For a straight landlord who is not a real estate professional, first-year losses may be suspended. The deduction is not lost. It waits until you have passive income or you sell the property. 

None of this is a reason to skip cost segregation. It is the reason to map where the deduction will land before you pay for a study, not after. 

Lane two: farm and ranch purchases 

This is the lane that gets overlooked, and for our ag clients it is often the biggest one. It is also not really a building cost segregation study. It is a purchase price allocation, and the difference matters. 

When you buy a farm or a ranch, the closing statement usually shows one price for the whole place. The land, the buildings, the wells, the fences, the corrals, the roads, all of it in a single number. Too often that whole number lands in a non-depreciable land account, or gets split only between land and the house. Bare land is never depreciable. But most of what is attached to it is, if someone takes the time to identify it. 

Doing the allocation means walking the property and putting each asset in its correct class. It generally sorts out something like this: 

• Bare land and the personal residence sit outside. Land is never depreciable, and a residence follows its own rules depending on whether it is personal-use or rented out. 

• General-purpose buildings, like a machine shed, are typically 20-year property. 

• Single-purpose agricultural structures, built for one livestock or horticultural function, are often 10-year property. 

• Constructed land improvements, such as certain roads, ponds, wells, and stock water systems, are generally 15-year property, depending on what they serve. 

• Grain bins and grain-handling equipment often fall into 7-year property. 

• Fencing and corrals need their own classification based on how they are built and used, rather than being buried in the land number. 

  
  

The exact class depends on what the asset is and how it functions, which is why this is asset-by-asset work and not a percentage off the top. Here is the practical payoff. Because bonus depreciation reaches property with a 20-year recovery period or less, even the general-purpose buildings can qualify, which a 39-year commercial shell never does. Even when the land itself is most of the purchase price, and on a lot of Montana ground it is, a meaningful share of the improvement value can still be bonus-eligible. It does not mean everything but the dirt is deductible. The residence, personal-use portions, and certain structural items sit outside. It means the opportunity is usually far bigger than the land-and-house split most closings default to. 

Two things bite ag buyers in particular. First, bonus depreciation on used property generally requires an arm's-length purchase from an unrelated party. Buy the home place from a parent or a sibling and the bonus on those used assets can be knocked out, though improvements you make afterward get their own analysis. Second, improvements that came with ground you bought years ago may also qualify for a look-back allocation and, when the method-change rules allow, a Form 3115 catch-up at the bonus rate of their original year. 

Why the study should be done right 

The tax law does not require a cost segregation study to be prepared by an outside engineering firm. Let me say that plainly, because you will see it marketed the other way. What the law and the IRS guidance actually reward is quality: a study prepared by someone with the construction, cost-estimating, and tax-classification experience to support the result, backed by documentation, tied to the applicable authority, and reconciled to your actual basis. 

That is a higher bar than a spreadsheet full of round-number percentages, or a figure handed to you by the person who sold you the property. The IRS Cost Segregation Audit Techniques Guide, updated in 2025, puts preparer expertise first on its list of what makes a quality study. Well-supported, third-party documentation tends to carry more credibility than an unsupported estimate from someone with a stake in the number. So we keep the roles split: we handle the tax strategy and your return, a qualified provider handles the engineering, and you are free to use any qualified firm you like. 

The straight-talk caveats 

A few things we always model before recommending a study, because they can change the answer: 

• Recapture on sale. Faster depreciation can turn more of your future gain into ordinary-income recapture. And do not assume a 1031 exchange erases it. Since 2018 those exchanges only defer tax on real property, and cost segregation deliberately peels out components that may count as personal property. Those pieces can fall outside the exchange and get taxed when you sell, even as the building and land roll over. If a sale or exchange is on the horizon, this needs real math. 

  
  

• Every situation is different. Most of our clients are Montana taxpayers, and Montana currently follows the federal rules closely with limited addbacks, so the state result usually tracks the federal one. That is not true for every client or every state, and rules change. We check your facts rather than lean on a rule of thumb. 

  
  

• Overreach. A study that classifies aggressively to hit a big headline number is the kind that does not hold up. Bigger is not the goal. Defensible is. 

Where we come in 

If you own a rental, a commercial building, or farm and ranch ground, whether you bought last year or fifteen years ago, it is worth a look. We start by telling you honestly whether a study makes sense for your situation, not by assuming it does. We quantify the benefit against your real tax picture, your entity structure, and your plans for the property, then fit the result into a multi-year plan so the deduction lands where it does you the most good. 

Here is the low-risk way to find out. Reply to this newsletter or call the office, and we will set you up with a no-cost ballpark from ETS on your actual property. They build it from your basis and property records, and they keep it deliberately conservative. It is a go or no-go gauge, not a promise of savings. If it clears the bar, ETS gives you the study price up front, and we run the real tax math against your return and your plans before you commit a dollar. 

Straight talk on the partnership: we have a referral arrangement with Engineered Tax Services, and here is exactly what it is. Swanson Agency receives a referral fee equal to 10% of the study fee when a client engages ETS through us. Neither that referral fee nor ETS's study fee is calculated as a percentage of the depreciation identified or the tax savings claimed, so nobody profits from a bigger number. We recommend them because they specialize in this work, they staff engineers here in Montana, and they produce the documentation a defensible study needs. We would send you to them on the merits regardless, and you are free to use any qualified provider you choose. 

Clear Thinking. Straight Talk.