Self-storage due diligence has five parts: financial records (T12, prior P&Ls, rent roll, bank statements, tax returns, tax, utility and insurance bills), the physical plant, legal and title, operations, and the local market. Each item exists to verify one input in your underwriting.
The checklist below maps every request to the input it confirms. If an item comes back different from what you assumed, you change that input and re-run the deal. You don't just note it in a file.
How to use this checklist
Most due diligence lists are just a list of documents. That misses the point. You request a document because your offer price rests on an assumption, and the document either confirms it or breaks it. So every table below has a third column: the underwriting input that item verifies.
Before diligence starts, write down the inputs your offer depends on: unit count and mix, occupied units, in-place rent by size, other income, collection loss, each expense line, post-sale property tax, market rent, months to stabilization and exit cap. Then treat each request as a test of one of those numbers. When a test fails, change the input in the Deal Analyzer and look at what happens to the price you can pay.
Financial
The financials establish what the facility earns today. The three sources to cross-check are the rent roll (what tenants owe), the T12 (what the books say was earned) and bank deposits (what actually arrived). The T12 and rent roll guide walks through a full reconciliation.
| Request | What to check | Underwriting input it verifies |
|---|---|---|
| T12, month by month | Twelve monthly columns, not a single annual total. Look for months that jump or drop, expense lines that appear once, and missing lines (management fee, payroll). | Current revenue by line, current expenses, current NOI |
| P&Ls for the prior 2–3 years | Direction of revenue and occupancy, whether expenses were ever higher, and one-time items the seller calls "normal." | Revenue growth after stabilization, expense growth, expense ratio |
| Rent roll (unit-level export) | Every unit: size, climate control, status, tenant rent, street rate, move-in date, paid-through date. Totals should match the unit count and square footage in the offering. | Unit mix, occupied count, in-place rent per size, loss to lease |
| Bank statements, 12 months, every operating account | Monthly deposits compared with T12 revenue for the same months. Strip out owner transfers, loans and insurance claims. | Effective gross income (what was actually collected) |
| Tax returns for the property or its entity | Gross receipts reported to the IRS compared with the T12. A seller who reports less on the return than on the T12 has a problem either way. | Credibility of the T12 revenue and expense totals |
| Property tax bills and the assessor record | The current bill, the assessed value, the tax rate, and how the jurisdiction treats a sale. Ask the assessor, not the seller. | Current property tax and projected post-sale property tax |
| Utility bills, 12 months | Electric load from climate-controlled buildings, lighting and gates; water and trash. Compare with the T12 utilities line. | Utilities expense; climate-control operating cost |
| Insurance policy and loss runs | Coverage, premium, deductibles and claims history. Get your own quote; the seller's premium may not transfer. | Insurance expense; any known risk that affects price |
Two items here tend to move the price most. The first is the bank deposits, because they are the one record of revenue the seller did not prepare. The second is the property tax bill: in many jurisdictions a sale can trigger a reassessment, so the tax you pay may be based on your purchase price rather than the seller's old value. Confirm how your county handles it with the assessor, and see the property tax reassessment guide for the math.
Physical
The physical inspection answers two questions: how many units can actually be rented, and how much capital you need to put in. Hire a property condition inspector, and walk the site yourself as well.
| Request | What to check | Underwriting input it verifies |
|---|---|---|
| Property condition report | An inspector's list of immediate repairs and a schedule of capital items by year, with cost estimates. | Acquisition costs, price adjustments, and cash you hold back from equity |
| Roofs | Age, material, leaks, prior repairs, remaining useful life. | Capital needs; whether any units are unrentable today |
| Roll-up and swing doors | Springs, latches, dents, rust, units that will not open. Count units that are offline. | Rentable unit count; the gap between physical and rentable units |
| Paving and drainage | Potholes, standing water near buildings, drive-aisle width for trucks. | Capital needs; lease-up (a rough site rents slower) |
| Gates and access control | Keypad or app-based entry, integration with the management software, gate hours, and whether overlock status syncs with delinquency. | Operating model (remote or staffed), payroll, collection loss |
| Cameras and lighting | Coverage, recording retention, working units. Buyers and insurers both ask. | Insurance, marketing position, capital needs |
| Climate-control HVAC | Units marked climate-controlled on the rent roll should be served by working equipment. Check age and service records. | Which units get climate-controlled market rent; utilities; capital needs |
| Unit audit (walk every door) | Match each door to the rent roll: locked with a tenant lock, vacant and open, overlocked, or company-locked. Do it yourself or have your manager do it. | Occupied count; delinquent units counted as occupied |
The unit audit is the cheapest test in the whole list. The rent roll says which units are occupied; the doors tell you whether a tenant's lock is actually on them. A unit shown as occupied that is standing empty with the door open, or that has been overlocked for four months, is not income. Take those units out of your occupied count in the unit mix. The physical vs. economic occupancy guide explains why the difference matters.
Capital items found in the inspection belong in acquisition costs or in a price reduction, not in your operating expenses. A roof replacement is not a repair line on the P&L.
Legal and title
Legal diligence confirms you are buying what you think you are buying, and that it can keep operating as a self-storage facility. Your attorney and title company run most of this, but you should read the survey and the zoning letter yourself.
| Request | What to check | Underwriting input it verifies |
|---|---|---|
| Survey | Boundaries, building footprints, encroachments, easements and any excess land. Ask your lender and title company whether they require an ALTA survey. | Rentable square feet; room for expansion |
| Title commitment | Liens, easements, restrictions and exceptions. Your attorney reviews and objects to what matters. | Whether the deal closes as priced; any use restriction |
| Zoning verification | Whether self storage is a permitted use, legal nonconforming, or needs a special permit, and what that means if a building is damaged or you want to add one. | Exit cap and value (a nonconforming use is riskier); expansion feasibility |
| Permits and certificate of occupancy | Permits and final inspections for every building, conversion and climate-controlled addition. | Whether units on the rent roll can legally be rented |
| Phase I environmental site assessment | A Phase I ESA under the ASTM E1527-21 standard. Findings may lead to a Phase II with sampling. | Acquisition costs; whether the lender will close; environmental liability risk |
Phase I environmental site assessment
According to the EPA, All Appropriate Inquiries (AAI) is “the process of evaluating a property's environmental conditions and assessing potential liability for any contamination.” The EPA's AAI rule, at 40 CFR Part 312, recognizes the ASTM E1527-21 Phase I standard as a way to comply. AAI is part of qualifying for certain liability protections under the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), including those for bona fide prospective purchasers, innocent landowners and contiguous property owners.
Timing matters. The EPA states that AAI must be conducted or updated within one year before the date you acquire the property, and that certain parts of it must be conducted or updated within 180 days before acquisition. A seller's two-year-old report does not meet that. Order your own, or have the consultant update it, and ask your lender what it requires. Your attorney can tell you what the findings mean for liability.
Operational
Operational records tell you how the facility is run, and where the T12 hides problems. They also give you the history you need to project lease-up.
| Request | What to check | Underwriting input it verifies |
|---|---|---|
| Management software exports | Occupancy by month, move-ins and move-outs, rate-change history, and the rent roll pulled directly from the system, not retyped into a spreadsheet. | Trend occupancy, months to stabilization, in-place rent |
| Delinquency aging and auction history | Balances by days past due, how many units went to auction, and whether notices followed state lien law. | Collection loss; true paying occupancy |
| Tenant protection or insurance program | Provider, monthly price, participation rate, the owner's share of the premium, and whether the program transfers to you. | Tenant protection income (scales with occupancy) |
| Fee schedule | Admin fee, late fees, lock sales. Compare the fee schedule with fee income on the T12. | Late fee and admin fee income |
| Contracts and leases | Management, software, call center, truck rental, cell tower, billboard, service contracts. Note term, termination rights and assignment. | Other income (retail, truck rental, other); operating expenses |
The delinquency report is the hardest test of the rent roll. A rent roll can keep a unit “occupied” until it is auctioned or vacated, even if the tenant has paid nothing for months. Count units more than 60 days past due separately and decide whether they are occupied for underwriting purposes. They are usually better treated as vacant units that you will re-rent, which lowers current NOI and raises the lease-up you need.
For the tenant protection program, compare participation with the number of occupied units. In the Deal Analyzer, tenant insurance, late fees and admin fees scale with occupancy, while retail, truck rental and other income do not, so getting the program's real monthly income right matters for both current and stabilized NOI. The ancillary income guide covers each line.
Market
Market work tells you what the facility can earn once you run it, which is the part of the price the seller's documents cannot verify.
| Request | What to check | Underwriting input it verifies |
|---|---|---|
| Supply pipeline | Facilities under construction, approved or proposed within your trade area. Call the planning department and drive the area. | Months to stabilization, target occupancy, exit cap |
| Street-rate survey of competitors | Web and phone rates by unit size, climate vs. non-climate, and current move-in specials at the facilities your tenants compare you with. | Market rent by unit size; rent-to-market upside |
For the rate survey, record each competitor's rate for the same unit sizes you own, split by climate control, and note any move-in special. Your market rent for each size in the unit mix should come from this survey, not from the seller's street rate. The rent roll analyzer shows loss to lease between in-place, street and market rent by unit size, which is where rent-to-market upside comes from.
Supply can break a lease-up plan. A new climate-controlled facility opening a mile away can lengthen your months to stabilization, lower the occupancy you reach, and, in a buyer's eyes at exit, justify a higher cap rate. Run the deal with a longer lease-up and a higher exit cap to see how much room you have.
What to ask for, and when
Documents usually arrive in stages. A workable order:
- Before the LOI: the T12, a summary rent roll, unit mix and the asking price. Enough to run a first pass and decide whether to offer.
- Once under contract: the unit-level rent roll export, month-by-month T12 and prior P&Ls, bank statements, tax returns, tax, utility and insurance bills, delinquency and auction history, contracts and the tenant protection details. Order the survey, title, Phase I and property condition report right away, since they have lead times.
- During the period: the unit audit, the competitor rate survey, the zoning and permit check, and conversations with the assessor and your lender.
- Before closing: an updated rent roll and delinquency report, dated as close to closing as possible, compared with the one you underwrote.
When diligence changes the price
Every finding lands in one of three places: current NOI, stabilized NOI or the capital you need. Here is how common findings map to inputs:
- Deposits below T12 revenue: lower current revenue, or raise collection loss.
- Delinquent units shown as occupied: lower the occupied count for those sizes; lease-up now has further to go.
- Tax bill will reset on sale: enter the projected post-sale property tax.
- No management fee or payroll on the T12: add them. The NOI calculator takes a line-item P&L.
- Roofs, doors or HVAC at end of life: add to acquisition costs or ask for a credit.
- Competitor rates below your assumed market rent: lower market rent by size.
- New supply nearby: lengthen months to stabilization and test a higher exit cap.
Then re-run the deal and compare with your targets. If the returns no longer work at the contract price, you have a specific, documented reason to renegotiate: the number that changed and the document that shows it. That is a stronger position than a general request for a lower price. For the full process from inputs to returns, see how to underwrite a self-storage deal.
- U.S. Environmental Protection Agency, Brownfields All Appropriate Inquiries (updated May 7, 2026).
This guide is general education about self-storage underwriting, not investment, lending, tax or legal advice. Figures from third-party reports are cited with their dates and change over time.