White Paper · Commercial Real Estate · Due Diligence

Commercial Property Due Diligence in Illinois: From Signed Contract to Closing

Once the purchase agreement is signed, every diligence task runs against a deadline. This paper explains what federal and Illinois environmental law require before and after closing, how title, survey and zoning fit in, what tenants should confirm, and which tax declarations are filed at closing.

By Lincoln Square Law · 12-minute read

You have signed a contract to buy a commercial building: a warehouse for your business, an investment property with tenants, or the storefront where your medical or dental practice will spend the next twenty years. The diligence period is usually your broadest right to walk away, and federal law puts a burden on you that many buyers discover late. Under the federal cleanup statute known as CERCLA, the current owner of a contaminated facility is liable for cleanup costs, subject only to narrow defenses (42 U.S.C. 9607(a)(1)). Those defenses depend on what you do before closing and what you keep doing afterward.

This paper picks up where our guide from letter of intent to closing leaves off: with a signed contract and a running clock.

Why a buyer inherits environmental liability

CERCLA makes the current owner and operator of a facility liable “subject only to the defenses” in subsection (b) (42 U.S.C. 9607(a)). One of them protects a person who shows the release was caused solely by a third party, but it excludes a third party connected to the defendant by a “contractual relationship,” and a deed is that kind of relationship (42 U.S.C. 9607(b)(3), 9601(35)(A)). A buyer cannot simply blame the prior owner. It needs one of the landowner protections Congress wrote into the statute.

Three statutory protections and what each requires

The bona fide prospective purchaser protection is the one most commercial buyers aim for because it works even when the buyer knows about contamination. It applies to a person that acquires after January 11, 2002 and meets eight criteria: disposal occurred before acquisition, it made all appropriate inquiries, it gives required notices, it takes reasonable steps, it cooperates and provides access, it complies with institutional controls, it answers information requests, and it is not affiliated with a liable party (42 U.S.C. 9601(40)). As long as it does not impede a response action it is not liable as an owner, although the United States may hold a lien for unrecovered costs, capped at the increase in value attributable to the cleanup (42 U.S.C. 9607(r)).

The contiguous property owner protection covers a buyer whose land is contaminated only by migration from a neighboring parcel it does not own. It requires appropriate inquiry and that the buyer did not know or have reason to know of the contamination, although a buyer that did know may qualify as a bona fide prospective purchaser (42 U.S.C. 9607(q)). The innocent landowner defense requires that, at acquisition, the buyer did not know and had no reason to know of the disposal after making all appropriate inquiries, plus the due care and precautions of the third-party defense (42 U.S.C. 9601(35)(A), (B), 9607(b)(3)). If the environmental report finds contamination before closing, this defense is usually gone.

All appropriate inquiries: the rule, the standard, and the dates

All three protections share a threshold: making “all appropriate inquiries” before acquisition under 40 C.F.R. Part 312. In practice a buyer meets the rule through a Phase I environmental site assessment under ASTM E1527-21, which EPA recognized in a final rule published December 15, 2022 (87 Fed. Reg. 76578). Under the eCFR text current as of this writing, the rule recognizes E1527-21, recognized the earlier E1527-13 only until February 13, 2024, and recognizes E2247-23 for forestland or rural property (40 C.F.R. 312.11).

The inquiries must be conducted within one year before acquisition, and five components must be conducted or updated within the 180 days before it: interviews with owners and occupants, the search for environmental cleanup liens, the review of government records, the visual inspection of the property and adjoining properties, and the environmental professional’s declaration (40 C.F.R. 312.20). Practice recommendation: calendar the date the 180-day window closes and order the update before agreeing to an extension.

The gap between a Phase I report and a defense

A Phase I report is not the defense. The rule assigns tasks to the buyer itself: the search for recorded environmental cleanup liens, its specialized knowledge, the relationship of the price to the value of uncontaminated property, commonly known information, and the degree of obviousness of contamination (40 C.F.R. 312.25, 312.28 to 312.31). The environmental professional, for its part, must give an opinion on conditions indicating a release, identify data gaps and sign its declaration (40 C.F.R. 312.21).

When the Phase I identifies a recognized environmental condition, the decision is commercial and legal at once: order a Phase II with sampling, negotiate price, indemnity or an escrow, or terminate. EPA’s 2019 “Common Elements” guidance states that it directs agency staff, is not a rule, and that courts are the final arbiter of whether a landowner met the requirements. Practice recommendation: get the consultant’s draft early enough before the diligence deadline to commission a Phase II.

Obligations that begin at closing

The bona fide prospective purchaser protection is not earned once. EPA’s guidance treats appropriate inquiry as a threshold requirement, and reasonable steps, cooperation, institutional controls, answers to information requests and notices as continuing obligations needed to keep it. Reasonable steps depend on the site. The guidance states that Congress did not intend, as a general matter, to impose a liable party’s response obligations on these owners, but the statute does require them to stop continuing releases and prevent exposure (42 U.S.C. 9601(40)(B)).

Practice recommendation: before closing, name one person to keep a compliance file holding the Phase I and any Phase II, land use controls, the reasonable steps plan, agency correspondence and an annual review.

Illinois liability and the Site Remediation Program

The Illinois Environmental Protection Act also makes the owner and operator of a facility with a release of a hazardous substance liable for the removal or remedial costs of the State or a unit of local government (415 ILCS 5/22.2(f)). It recognizes a defense for a buyer that acquired without knowledge after appropriate inquiry consistent with good commercial practice, and a presumption for a buyer that obtains, immediately before or at acquisition, a Phase I or Phase II audit disclosing no hazardous substances. If the Phase I discloses a likely release and no Phase II is obtained, there is no presumption (415 ILCS 5/22.2(j)(6)). The state text still refers to an older version of the ASTM standard, so the consultant should confirm the report serves both statutes.

If the property went through the Site Remediation Program, which is risk-based according to present and future use (415 ILCS 5/58), ask for the No Further Remediation (NFR) letter. The letter releases the applicant from further responsibilities under the Illinois Act and is prima facie evidence that the site poses no threat, provided it is used in keeping with its terms (415 ILCS 5/58.10(a)). It is effective only once recorded, and then it becomes a permanent part of the chain of title (415 ILCS 5/58.8). It benefits later owners and lenders, but it becomes voidable if its use limitations are violated, controls are not maintained, or contamination left in place is disturbed (415 ILCS 5/58.10(d), (e)). If you plan a change of use, such as warehouse to clinic, confirm the letter allows it. In our reading, the letter resolves state liability and does not replace the federal analysis.

Title, survey, and what is on the ground

Reading the title commitment is covered in our white paper on title commitments and Schedule B. In a commercial purchase its companion is the ALTA/NSPS survey. The 2026 standards, adopted by the American Land Title Association and the National Society of Professional Surveyors, took effect February 23, 2026. They require that the surveyor receive the most recent title commitment, the record description and the recorded easement and restriction documents, and they include Table A, a list of optional items the client selects. Practice recommendation: send the commitment to the surveyor as soon as it arrives and choose the Table A items your use needs, such as flood zone or parking counts.

Zoning and lawful use in Chicago

In Chicago, the Zoning Ordinance, Title 17 of the Municipal Code, determines whether a use is permitted, needs special approval or exists only as a nonconforming use, meaning one lawfully established under earlier rules that no longer complies (Chicago Municipal Code 17-15-0301). It can change to a permitted use or, with approval, to a similar use of no greater impact, and expansion requires approval (17-15-0302, 17-15-0303). The risk that most surprises buyers is loss by discontinuance: a nonconforming use ends after 18 continuous months without operation, and certain uses after 6 months (17-15-0304-A). An empty building may have lost the use that justified the price.

Practice recommendation: ask the seller for certificates of occupancy and permits, obtain a zoning letter from the city or a zoning analysis from the surveyor, and confirm that your specific use, such as a medical or dental office, fits the classification. If the property is mixed-use with a few dwelling units, check whether the city requires a certificate of zoning compliance before it issues transfer tax stamps (Chicago Municipal Code 3-33-045).

Leased buildings: estoppel certificates and SNDAs

If the building has tenants, you are also buying their leases. Each tenant’s estoppel certificate confirms the rent, the deposit, the term dates, any renewal, purchase or first-refusal option, and whether defaults or claims exist. Your lender will likely also require subordination, non-disturbance and attornment agreements (SNDAs) with major tenants. No statute requires these documents. They are market practice, and the contract should obligate the seller to request them and say what happens if a tenant does not sign. Practice recommendation: compare each certificate with the lease and rent roll before the diligence deadline, and treat any tenant purchase option as a title issue. Our healthcare lease red-flag checklist covers the SNDA from the tenant’s side.

Transfer tax declarations at closing

Illinois taxes the privilege of transferring title to real estate, a beneficial interest, or a controlling interest in an entity that owns real estate (35 ILCS 200/31-10). A deed will not be accepted for recording without a declaration signed by at least one seller and one buyer, or their attorneys or agents, stating the value, the parcel number and the legal description (35 ILCS 200/31-25). Chicago’s tax on the transfer of title or a beneficial interest falls primarily on the buyer, and a supplemental tax falls on the seller (Chicago Municipal Code 3-33-030). Both sides sign the city declaration, and no exemption is recognized unless the declaration describes the facts supporting it (3-33-070). Practice recommendation: confirm early who pays each tax under the contract and assemble support for any exemption before closing week.

A diligence calendar tied to the contract deadlines

A late termination notice usually means the condition is waived, so every contract deadline needs a date and an owner. The sequence below is a practice recommendation, not a legal requirement.

• At signing: calendar every deadline and notice requirement, order the Phase I, title commitment and survey, and request leases, prior reports, NFR letters, permits and certificates of occupancy from the seller.
• First half of diligence: request the zoning letter, send the commitment to the surveyor, circulate estoppel certificates and complete your own inquiry tasks.
• Before the diligence deadline: review the draft Phase I, decide on a Phase II, reconcile estoppels with leases, and serve objections or the termination notice on time.
• Before closing: confirm the 180-day window will still be open on the closing date, obtain the lender’s SNDAs and prepare the state and city declarations.
• After closing: open the continuing obligations file and schedule the first annual review.

What the acquisition file should keep

If an agency or a future buyer later asks what you did, the answer will be in the file: the contract with every notice sent, the Phase I and any Phase II with the professional’s declaration, the lien search, a note on price against value, the NFR letter, the title policy, the survey, the zoning letter, the estoppels and SNDAs, and the transfer declarations, with a short index of what was still open.