The due diligence period is the part of the contract where you are allowed to replace a listing with documents. When it ends, the remaining surprises are yours. A long checklist feels like safety. It is only safety if each item can change the price, the terms, or your decision to leave, and if you assigned a person and a date to it.

Use the twelve checks that should move an offer before you send a number. Use this list after the offer is accepted, on a one-to-four unit rental. Larger buildings need more of the same logic: prove the income, prove the condition, prove you can use the building the way you intend, and prove you can leave the investment later. None of this is a substitute for an inspector, a title company, or a local attorney.

Income and leases, items 1–12

  1. A rent roll that names every unit, every tenant, the rent, the deposit, and the lease dates.
  2. Every lease and every amendment, not a summary the seller typed.
  3. Estoppel letters, or your state’s equivalent, in which the tenant confirms rent, deposit, and any side deal.
  4. A trailing year of income and expenses, with the months labeled.
  5. Bank deposits or a ledger that you can match to the rent roll for a sample of months.
  6. The current tax bill, plus a written question to the assessor or title company about whether a sale resets the assessment.
  7. An insurance quote in your name for this address, including liability and loss of rent if you intend to carry them.
  8. Utility bills for any service the owner pays, long enough to see a winter and a summer.
  9. Service contracts — laundry, pest, waste, landscaping — and whether they bind the next owner.
  10. Where security deposits sit, and whether that account matches your state’s rule.
  11. Delinquencies, payment plans, and any pending eviction, with the court name if one exists.
  12. Your own income model, built from those papers, not from the flyer. The underwriting sequence is the order. The expense stack is the list of lines the flyer folds into a single percent.

If the seller will not produce the leases, you are not in diligence. You are in a negotiation about whether to extend or to leave.

The building itself, items 13–30

  1. A full inspection by someone who will walk every unit, not a sample “because they are all the same.”
  2. Roof age and condition, from the inspector and from permits if the city keeps them.
  3. Foundation and structure: cracks, slope, prior water.
  4. Heat and cooling equipment, age and service records, unit by unit.
  5. Water heaters, age and venting.
  6. Electrical service: panel size, and any equipment the inspector flags for replacement.
  7. Plumbing materials. Galvanized, polybutylene, cast iron, copper, and PEX fail differently. The inspector should name what is there.
  8. A camera in the sewer lateral. A scope is a video, not a guess from the lawn.
  9. Moisture and ventilation in basements, attics, and baths.
  10. Windows and doors that actually close.
  11. Smoke and carbon-monoxide alarms where your code requires them.
  12. Lead-based paint disclosure for housing built before 1978. The EPA explains that sellers and landlords must give buyers and renters the lead pamphlet, disclose known lead-based paint and hazards, and provide available records. Paint in good condition is a different fact from paint that is peeling. Do not treat “pre-1978” as a vibe; treat it as a disclosure file.
  13. Other hazardous materials the inspector calls out, including suspected asbestos in older finishes. Testing is a scope, not a paragraph.
  14. Radon, where the local practice or your lender expects a test. A test is a number from a device, not a neighborhood reputation.
  15. Wood-destroying insects, where that inspection is customary or the lender requires it.
  16. Grading, gutters, and where water goes in a hard rain.
  17. Walks, stairs, and parking surfaces people can trip on.
  18. A personal walk of every unit with the inspection report in your hand, so “tenant would not allow access” is a known hole, not a footnote you discover after closing.

Each physical finding becomes a credit, a price change, a repair the seller completes, or a reason to use the contingency. A finding you will not walk away over is not leverage. Decide that before you ask for the credit.

  1. Title commitment and the exceptions. Title insurance defends covered defects in the chain. It does not repair a roof. Read the exceptions for easements and access.
  2. Survey or boundary evidence if access, a fence, or an addition is in doubt.
  3. Zoning that allows the number of units you think you are buying. A finished basement is not a unit because it has a stove.
  4. Permits for additions and for work you can see is newer than the house.
  5. Open code cases and municipal liens.
  6. Rental registration or inspection programs you must pass before you may lease.
  7. Rent regulation, if your city has it, and whether the current rents are legal rents or a mistake.
  8. Short-stay rules, only if your plan depends on them. If it does not, do not pay for a fantasy about weekend rates.
  9. Association documents: rules, budget, reserves, insurance, rental caps, and any special assessment that has been discussed. Minutes are more honest than the resale certificate’s summary.
  10. Flood zone. Ask the insurer and the lender whether the building is in a Special Flood Hazard Area on a FEMA flood map, and what a policy would cost. A required flood policy is a carrying cost, not a surprise at the closing table.
  11. Litigation involving the property, the association, or a tenant you would inherit.

The block around the building, items 42–47

  1. Leased comps for each unit type, with addresses and dates, not a portal estimate.
  2. Closed sales you would actually show an appraiser, if a loan depends on value.
  3. How long units on this street sit empty between tenants, from managers or from the leases’ gaps, not from a national vacancy adjective.
  4. Road, zoning, and construction plans the city has already filed, if they change noise, access, or the view you paid for.
  5. Visits at the hours tenants live there, including after dark. A crime map without a visit is a screenshot.
  6. Why people pay rent here: employers, transit, a campus. If you cannot name the reason, you are guessing at the lease renewal.

Loan and exit, items 48–50

  1. Whether the appraisal, if the loan uses one, supports the price and the rent the lender will count. A DSCR program and a conventional loan do not count rent the same way. The DSCR guide is the list of questions for that kind of sheet.
  2. The loan estimate in final form: rate, fees, reserves, and any prepayment penalty, matched to the payment you used in your cash-flow page.
  3. An exit that is not “someone will pay more later.” Name the buyer: an owner-occupant, a small landlord, or a lender for a refinance. If none of those can be described with today’s rules, the price is a story.

How to run the period so it does not expire by accident

Put the fifty items on one page with a column for owner, a column for the date you asked, and a column for price, term, or walk. Inspection appointments go on the calendar the day the contract is signed, because inspectors are not waiting for you. Document requests go out the same day. Credits get contractor numbers, not round figures you hoped sounded serious.

The glossary entry for the due diligence period says a weekend on a fourplex is how you buy the sewer. Believe it. If the contract’s window is shorter than the inspections, extend it or do not waive it to look aggressive.

When the list is done, the offer you already made is either still a price you want, a price you want changed, or a contract you should leave under the contingency you kept. That is the only score the checklist has.

This list is general education. Inspection standards, disclosure duties, and contract deadlines are local. Your attorney and your inspector outrank a website, including this one.

Field notes

Fifty-item lists are how inspection weeks go. They are the wrong object the night you write the offer. Use the twelve checks that should change price or kill the deal first. Then, after acceptance, work the long list with a calendar: inspector, sewer scope, insurance bind, HOA resale pack, lease audit.

If a 50-point article still reads like every other AI outline — “check the roof, check the title” — the missing piece is usually which item is a credit versus a walk. Write that in the margin before you send the inspector in. A roof you will replace is a number. A flood policy you cannot bind is a pass.