Technically, nothing stops you from preparing your own cost segregation analysis, and some software tools are built for it. But the IRS expects a study to be prepared by someone with expertise, using a reliable method and real documentation. DIY can make sense for small, simple rentals with modest deductions. For larger properties, the audit risk usually outweighs the savings on fees.
This content is not tax or financial advice for you. Please talk with a CPA to find what's right for your situation.
Is DIY cost segregation allowed?
There's no law that requires a licensed engineer to prepare a cost segregation study. However, the IRS Cost Segregation Audit Techniques Guide says a quality study should be prepared by an individual with knowledge and experience in the field. It also ranks "rule of thumb" methods, like applying a flat percentage, as the least reliable.
So DIY is allowed, but it's held to the same standard as a professional study if it's ever examined.
What a DIY approach usually looks like
Most do-it-yourself efforts follow a residual estimation approach:
- Start with the depreciable basis (purchase price minus land).
- List the short-life items you can see: appliances, flooring, cabinets, light fixtures, fencing, driveway, landscaping.
- Estimate each item's cost using receipts, contractor quotes, or published cost data.
- Assign each item to a 5-, 7-, or 15-year class.
- Assign the remaining cost to the building.
- Document everything with photos and sources.
DIY vs. software vs. professional
| Factor | Pure DIY | DIY software | Professional study |
|---|---|---|---|
| Cost | Your time | Usually a few hundred to under $2,000 | Usually $2,000 to $15,000+ |
| Expertise | Yours | Built-in cost data and rules | Engineers and specialists |
| Site inspection | You | You (photos) | Specialist, in person or virtual |
| Report quality | Varies | Standardized | Detailed |
| Audit support | None | Varies | Often included |
| Best for | Very small, simple properties | Small rentals | Most properties over roughly $500,000 |
The biggest DIY risks
- Misclassifying structural items. Walls, roofs, and general plumbing and electrical belong to the building. Putting them in 5-year property is a common error.
- Weak cost support. Guessed numbers are easy for an examiner to reject.
- Poor reconciliation. Your allocations must add up exactly to your basis.
- No defense. If the IRS asks questions, you're on your own.
- Penalties. If deductions are disallowed, you may owe interest and possibly accuracy-related penalties.
When DIY might make sense
- The building value is modest, and the deduction at stake is small
- You have strong records, like itemized renovation invoices
- You're mainly separating obvious items, such as appliances and furniture you bought
- Your CPA reviews your work before filing
A middle path
Many small investors get a lower-cost professional study, often with a virtual tour, instead of going fully DIY. It costs more than software but gives you a credentialed preparer and some audit support.
Frequently asked questions
Can I just use 25% as my reclassification?
Can I deduct furniture and appliances without a study?
Will my CPA accept a DIY study?
See what your property may qualify for
Run our 2-minute STR Qualification Quiz or model your Low / Mid / High cost segregation range.
Related guides
Types of Cost Segregation Studies Compared
Engineering-based, residual, sampling, look-back, new construction: compare the main types of cost segregation studies and when each makes sense.
Read guideIRS Cost Segregation Requirements: What a Quality Study Must Include
The IRS spells out what a quality cost segregation study looks like. Use this plain-English checklist to judge a study before you rely on it.
Read guideCost Segregation Companies: Engineering Firms vs. CPA Firms vs. Software
Engineering firms, CPA firms, or online software? Compare the main types of cost segregation companies on cost, detail, audit protection, and fit.
Read guideHow Much Does a Cost Segregation Study Cost? 2026 Price Guide
What does a cost segregation study cost? See typical 2026 price ranges by property type, what drives the fee, and how to tell if it pays off.
Read guideThis content is not tax or financial advice for you. Please talk with a CPA to find what's right for your situation.