In one paragraph
On a $600,000 rental, getting two numbers right, the land value and the closing costs, can move your first-year deduction by about $11,200. A DIY tool asks you for the answers. A study finds them, and that is where the money is. DIY tools and our studies start at about the same price, and both classify components under MACRS per Rev. Proc. 87-56. What differs is where the inputs come from: in a DIY tool they come from you, while a study reads your closing statement, sets land from documents or county records, and checks that everything adds up to your basis before it reaches your CPA.
Disclosure: Cost Seg Smart operates this comparison and is one of the options compared here. See the methodology page for our standalone documentation.
Choosing between specific tools? See cost segregation software compared, which puts the self-service tools, engineer-reviewed tiers and done-for-you providers side by side with their published prices.
Where the number is won or lost
The form is the easy part. The deduction is decided by a few inputs, and the two that move it most are the ones a buyer is least likely to know offhand: how much of the price is land, and which closing costs belong in basis. On a $600,000 single-family rental:
| If this input is off | What happens | First-year deduction affected |
|---|---|---|
| Land overstated by 10 points of the price | $60,000 of building is treated as land, which is never depreciated | $10,005 |
| $9,000 of capitalizable closing costs left out | $7,200 of depreciable basis never makes it onto the schedule | $1,201 |
| Together | About $4,146 of federal tax at the top bracket | $11,206 |
On a condo unit at the same price, counting your share of the shared outdoor site improvements can add up to about $15,900 more in the first year, because that share moves from the 27.5-year building to 15-year property.
Illustrative example, not a projection: a single-family rental bought and placed in service in 2026, with the representative reclassification share used across this site. Your numbers depend on your property, your documents and your tax situation. Missed depreciation is mostly timing; land and closing costs left out of basis are not depreciated at all.
What a study does that a form can't
Land, from evidence
Land is the one part of the price you can never depreciate, so every point of land you overstate is deduction you never get. We set land from your own documents or from public county records where they exist, check assessor figures for reliability, and the report names the source we used.
We read your closing statement
Capitalizable closing costs belong in your basis; leave them out and that part of your purchase is never depreciated. Upload your settlement statement and any itemized invoices or cost schedules and we read them: capitalizable closing costs go into your basis, documented costs are classified line by line, and a cost document we cannot read holds the study for review instead of being skipped.
Your share of the condo's site work
A condo owner holds an interest in the shared grounds, and part of that is 15-year property that can be deducted far sooner than the building. Where a residential condo unit includes an ownership interest in the common elements, the study may allocate a conservative portion of the unit's existing basis to the shared outdoor improvements it identifies, such as parking, landscaping and fencing, as 15-year property. It reallocates basis you already have; it does not add any. Pools, clubhouses, gyms and other building amenities are not included. Condominium law normally gives each unit an undivided interest in the common elements, so the share is included even if you did not know you held one.
Reconciled to your basis, to the cent
A schedule that does not add up to your basis is the first thing a CPA or an examiner questions. Every component schedule adds up to your depreciable basis to the cent, and a study that does not is automatically blocked before delivery.
Quality-checked before delivery
Problems are caught before your CPA files, not after. Every study is automatically quality-checked before delivery, and a study that fails a check is held rather than sent.
Questions to ask any DIY tool or provider
Whatever you choose, these are the questions that decide the number. A good tool or provider answers them plainly.
- Where does the land value come from, and does the report say which source was used?
- Does it read your closing statement, or do you type the numbers in yourself?
- On a condo, does it count your share of the shared outdoor site improvements, or only the unit?
- Does the schedule reconcile to your depreciable basis, and what happens if it does not?
- What is checked before the report reaches you, and what happens when a check fails?
At a glance: residential $500K rental
| Dimension | Cost Seg Smart | DIY tool |
|---|---|---|
| Price (residential $500K) | $895 | Starts at about the same price; published prices by tool |
| Where the inputs come from | Your closing statement and documents, county records, and a short order form | Usually a short form, with the answers coming from you |
| Who classifies components | Our engine, under MACRS per Rev. Proc. 87-56 | The tool, from what you enter |
| Checks before delivery | Quality-checked; a study that fails a check is held | Varies by tool; a reviewed tier often costs more |
| Audit support | Lifetime written audit support, included | Varies by tool; often an add-on |
| Form 3115 look-back | §481(a) catch-up schedules and workpapers included | Varies by tool |
| Free revision policy | Free for 12 months after first delivery (36 months for your CPA's requests), then $195 per round; corrections of our errors always free (original scope of the study) | Re-enter your data |
| CPA coordination | CPA coordination included. We answer your accountant's technical questions in writing, provide supporting schedules, and get on a call or meeting with your CPA when either of you asks. | Varies by tool |
When DIY is the right call
- The basis is small and you want a rough number. On a low-basis property the reclassifiable dollars may be small either way. For a ballpark before you buy anything, the free calculator answers the question too.
- You already know your land value and your closing costs cold. If you have an appraisal with a land allocation and your settlement statement in hand, a DIY tool's biggest weakness, the inputs, is one you have already solved.
- You want to do the classification yourself. If you have a tax or construction background and want full control of each choice, DIY puts you in the driver's seat. The hard part is the line the IRS draws between a building's structural components and the personal property inside it, which turns on how an item is attached and how permanent it is (Treas. Reg. §1.48-1(e) and the permanence factors courts apply).
- A spreadsheet is the free version. You can list components and apply MACRS lives in Excel at no cost; see our cost segregation Excel template. Self-estimated component costs are the weakest support if the return is examined, so it suits a rough check more than a filing.
- You are a CPA learning the method. Running a DIY tool once or twice is a reasonable way to understand the framework before recommending a provider to clients.
How to decide
- Do you know your land value and which closing costs belong in basis? If not, those two inputs are worth more than the fee on most rentals; see the example above.
- Is the property a condo? Ask whether the tool counts your share of the shared outdoor site improvements, or only the unit.
- Do you want someone to answer your CPA's questions? Our studies include CPA coordination and lifetime written audit support; with a DIY tool that depends on the tool and the tier.
To estimate Year-1 savings on your property, run the free calculator. Full methodology is at /methodology/, and pricing at /pricing/.
Last updated: November 2026. Maintained by the Cost Seg Smart Editorial Team. This comparison is informational. DIY tools differ, so confirm current pricing and features directly with each vendor.