How to Properly Document a Renovation for Cost Segregation

Construction materials and scaffolding surrounding a house renovation

RENOVATION DOCUMENTATIONAugust 2026

Every renovation dollar you submit should have a receipt or invoice behind it. Basis does not need that paperwork just to run the analysis. It needs it because the costs in a cost segregation study should be traceable to supporting records. If the numbers do not tie out to the documentation, the submission is returned before analysis begins.

Basis organizes each renovation submission into 16 categories, including Project Details and 15 cost categories. Project Details captures the completion date and total renovation cost.

Project Details

Field	What It Means	Why It Matters
Completion date	The date the renovated space was finished and usable again, not the date you paid the contractor.	Depreciation generally begins when property is placed in service, meaning it is ready and available for its intended use. A project finished December 28 and one finished January 3 can fall into different tax years.
Total	The full cost of the renovation event.	This amount should match the sum of the supporting receipts and invoices. A round number without documentation is difficult to support if questioned.

One renovation, one submission. Each distinct renovation event is priced and evaluated separately rather than bundled with unrelated projects.

Structural and Systems

These invoices often combine repair and improvement costs. Keep those amounts separated when possible instead of submitting one lump sum.

Category	What Belongs Here	Documentation Note
Structure	Framing, load-bearing changes, and foundation work tied to the renovation.	Use a contractor invoice that describes the scope of work, not just the total charge.
Plumbing	New fixtures, repiping, and water heater replacement.	Repairs such as fixing a leak and improvements such as replacing a system are not treated the same for tax purposes. If an invoice combines both, ask the contractor to itemize it.
Electrical	Rewiring, panel upgrades, and new circuits.	Keep repairs and improvements separated. Avoid submitting one electrical total when the invoice covers different types of work.
Lighting and Low Voltage Systems	Fixtures, smart-home wiring, security systems, and networking infrastructure.	Keep these costs separate from general electrical work when they were invoiced separately. If the contractor combined them, request a breakout when possible.
HVAC	New systems, ductwork, and mini-splits.	Equipment invoices should show the equipment cost separately from installation labor when possible.

Interior Finishes

Interior finishes often represent a large share of renovation spending. For short-term rentals, appliances and furnishings deserve extra attention because their depreciation treatment can differ from the building itself.

Category	What Belongs Here	Documentation Note
Flooring	New flooring of any material. Refinishing can also be included when it is part of a broader renovation.	Receipts should show square footage or a room-by-room breakdown when available.
Cabinetry	Kitchen, bathroom, and built-in cabinetry.	Keep the cabinetry cost separate from installation labor when the contractor's invoice allows it.
Wall Finishes and Trim	Paint, wallpaper, molding, and trim work.	Cosmetic touch-ups outside a broader renovation may not qualify as capitalizable improvements. Keep this category limited to work connected to the renovation event.
Fans and Window Coverings	Ceiling fans, blinds, shades, and drapery hardware.	Keep the receipt or invoice supporting the purchase.
Appliances	Refrigerators, ranges, dishwashers, washers, and dryers.	Keep individual appliance receipts rather than a single undocumented appliance-package total when possible.
Mounted Items and Furnishings	Wall-mounted TVs, artwork installation, and furniture packages.	For short-term rentals, document furnishings separately when possible. Furnishings can represent a larger share of the project cost, and their depreciation treatment may differ from the building or other improvements.

Exterior and Site

Category	What Belongs Here	Documentation Note
Paving, Patios, and Walks	Driveways, walkways, and patio surfaces.	Use contractor invoices showing square footage when available.
Decks	New decks, deck replacement, and major deck repair.	Keep deck costs separate from general structural work if the contractor invoiced them together.
Pools and Hot Tubs	Installation and major equipment replacement.	Separate equipment such as pumps and heaters from the pool or hot tub structure when the invoice provides enough detail.
Landscaping and Other Site Improvements	Irrigation, retaining walls, and major landscaping.	Routine lawn maintenance is not a renovation cost. Limit this category to capital improvements connected to the renovation event.

A Note for Short-Term Rental Owners

Short-term rental renovation costs should not automatically be treated as though every property were a standard long-term residential rental. Tax classification depends on the facts. IRS Publication 527 distinguishes residential rental property from a hotel, motel, inn, or other establishment where more than half of the units are used on a transient basis. That distinction can affect the depreciation treatment of the building and its components. If you are unsure how your property is classified, have the treatment reviewed before applying long-term rental assumptions to the renovation.

Before You Submit

Every category total ties back to an itemized receipt or invoice rather than a round estimate.
Repair costs are separated from improvement costs, especially on plumbing and electrical invoices.
The completion date reflects when the renovated space was finished and usable, not when the contractor was paid.
If you are unsure which category something belongs in, flag it rather than guessing. A flagged item is easier to resolve than a miscategorized one.

Incomplete submissions are returned before analysis begins. A few extra minutes organizing the documentation can prevent an unnecessary resubmission later.