The 30-second answer
Yes, you can do cost segregation yourself, and for some properties it is reasonable. DIY works best when the basis is small, you only want a rough estimate, and you are comfortable with more audit risk. The catch is that the IRS expects component costs grounded in engineering or construction-cost data, not round-number self-estimates, so a do-it-yourself schedule is weaker if it is ever examined. A professional study makes sense when the dollars are large enough that getting the classification right (and defended) is worth more than the fee. Because an automated study starts at $495, the gap between DIY and done-for-you is now small enough that the math usually favors a real study.
The three DIY paths
- Excel / spreadsheet (about $0). You categorize components yourself and apply MACRS lives. Free, but you are supplying your own cost estimates, which is exactly the part the IRS scrutinizes.
- DIY software (about $100 to $500). Tools such as a residential cost-segregator give you a component library and a schedule generator, but you still do the data entry, confirm the classifications, and assemble the report, typically a few hours of work, and you own the result.
- Done-for-you study (from $495). An engineering-based or automated provider produces the full schedule and a CPA-ready report addressing the IRS quality framework, with audit support. No customer labor and a defensible deliverable.
What each approach costs
| Approach | Cost | Who does the work / risk |
|---|---|---|
| Excel / spreadsheet | $0 | You; self-estimated costs carry the most audit risk |
| DIY software | $100 to $500 | You (a few hours); you own the classifications |
| Cost Seg Smart | From $495 | Done for you; internal technical review & QC, audit support |
| Traditional firms | $2,000 to $10,000+ | Done for you; engineer-led, multi-week |
DIY software prices vary by vendor; confirm current pricing directly. Cost Seg Smart's residential ladder runs from $495; see /cheap-cost-segregation/.
When DIY may make sense
- The basis is very small. On a sub-$150K property with few improvements, the reclassifiable dollars may not justify any paid study, and a rough self-estimate is enough to decide.
- You only want a ballpark. If you are deciding whether to pursue a study at all, a DIY estimate (or our free calculator) answers the question without a purchase.
- You are comfortable with more audit risk. Self-estimated component costs are weaker support than engineering-based costs if the return is examined; if you accept that trade-off on a small deduction, DIY can be fine.
When a professional study makes sense
- Basis around $300K or more. The Year-1 dollars are large enough that classification accuracy and a defensible report are worth far more than the fee.
- Bonus depreciation matters to you. Reclassified 5-, 7-, and 15-year property qualifies for 100% bonus under §168(k); a clean study maximizes what flows in Year 1.
- Commercial property. More systems, more components, more classification judgment, exactly where engineering-grade cost data pays off.
- Your CPA wants support. Many CPAs will not file an aggressive depreciation schedule without a documented methodology behind it.
- Audit defense matters. A study that addresses the IRS Cost Segregation Audit Techniques Guide (Pub 5653) is what holds up under examination; a spreadsheet usually is not.
What the IRS actually wants
The core of a defensible study is component costs grounded in construction-cost data and classified to the correct MACRS lives per Rev. Proc. 87-56 (IRS Pub. 946 Appendix B), documented against the 13-element framework in the IRS Cost Segregation Audit Techniques Guide. DIY tools can get you part of the way, but the cost basis and the methodology narrative are where self-prepared schedules tend to fall short. That is the gap a done-for-you study closes, and at $495 it closes cheaply. For a deeper look at the software route specifically, see Cost Seg Smart vs. DIY cost-seg software.
The bottom line
DIY is a legitimate choice on small properties where you want a rough number and accept more risk. Once the basis is meaningful, the deduction is large enough that a real study, with engineering-grade cost data, a documented methodology, and audit support, is the better expected value, and an automated study from $495 has made that an easy call for most investors. Run your property through the free calculator to see the Year-1 number, then decide.
Related: cost segregation software · DIY Excel template.