Introduction
One party often commissions a Phase I Environmental Site Assessment—then everyone else in the deal wants to use it too.
Typical requestors include:
- Sellers preparing disclosure or sale documentation
- Buyers reviewing the report during due diligence
- Lenders relying on it for underwriting
- Government-backed financing programs with their own reliance rules
Here's the catch: reviewing a report isn't the same as having the right to rely on it. The consultant who prepared it typically limits contractual reliance to whoever hired them. Everyone else may be reading a document they have no authorized claim to.
That's where a reliance letter comes in. This article covers what the letter actually does, who typically requests one, what it should contain, where its protections stop, and how to tell whether your transaction needs a fresh assessment instead.
Key Takeaways
- A reliance letter extends Phase I report rights to named parties; it is not a new assessment.
- It does not certify a clean property or automatically meet lender or SBA requirements.
- Verify report date, ASTM standard, relying parties, and program forms before closing.
- Only the original environmental professional can issue one and set its terms.
What Is a Phase 1 Environmental Reliance Letter?
A Phase I ESA is a non-invasive environmental due diligence report. It reviews historical land use, regulatory records, and site conditions to flag recognized environmental conditions (RECs) before a transaction closes. A reliance letter is a separate document: the original environmental professional authorizes a specifically named third party to use that existing report.
Receiving a copy of a report is not the same as having contractual rights to rely on it.
Why privity matters: Most Phase I engagements limit contractual reliance to the client who hired the consultant. A buyer or lender who wasn't part of that original agreement generally can't assert claims against the consultant without separate authorization.
ASTM E1527-21 makes this explicit: the standard itself does not convey a right to rely on someone else's assessment. Whether a letter actually fixes that gap depends on its wording, the underlying engagement agreement, and applicable state law.
The reliance letter does not recreate the underlying investigation. It points back to the original report rather than repeating that work, including:
- Interviews and records review
- Site inspection
- Findings and conclusions
The CERCLA Connection
Under the All Appropriate Inquiries rule, a new user may use a report prepared for someone else as part of meeting due diligence obligations. 40 CFR 312.20 still requires that user to review the report and complete their own applicable inquiries. That duty does not hinge on a consultant issuing a letter. A reliance letter is not proof that AAI obligations have been satisfied.
A common scenario: A buyer is offered a seller's recent Phase I report, but the report restricts reliance to its original client. The buyer asks the consultant for permission to rely on it rather than commission a new assessment, and still must confirm the report's inquiry dates meet current requirements.
As one environmental law commentary on reliance letters notes, permission and regulatory compliance are separate questions. The same report can draw multiple reliance requests, for example:
- Seller (original client)
- Buyer (new reliance letter)
- Lender (its own letter on the same investigation)
Who Requests and Issues a Reliance Letter?
Purchasers and lenders request reliance letters most often, but the list runs wider:
- Borrowers refinancing property covered by an existing report
- Sellers accommodating a buyer's lender
- Government-backed financing participants (SBA loans, for example)
- Community development organizations and insurers
- Original clients authorizing new parties to use the report
Only the firm or professional who prepared the underlying report can issue the letter. A different consultant reviewing someone else's work should not extend reliance on findings it did not produce. Professional liability attaches to the firm that signed the original report.
Sometimes the original client's written sign-off is required first, especially if the engagement agreement restricts disclosure or third-party use of the report.
Program-Specific Rules Vary Widely
Ordinary transaction requests differ from program-driven ones. Consider how three major lending frameworks handle this:
| Program | Requirement |
|---|---|
| SBA SOP 50 10 8 (effective 2025) | Requires its own Appendix 5 letter addressed to both the lender and SBA, even when the report already names the lender |
| Fannie Mae Form 4251 (April 2025) | Builds reliance language into the report for the lender, Fannie Mae, and successors; the borrower cannot rely on a lender-ordered report |
| Freddie Mac Multifamily Guide | Requires specified reliance language in the report for the seller/servicer, Freddie Mac, and identified financing participants |
Match the letter to the program in play. Confirm the current form, required addressees, and insurance documentation before you request signature.
Finally, don't assume the consultant will say yes. Extending reliance increases their professional liability exposure. They can decline, require an update, charge an additional fee, or negotiate limitations before agreeing to sign anything.
What Should a Phase 1 Reliance Letter Include?
Neither ASTM nor the AAI rule prescribes a universal reliance-letter template. What actually governs the content is the lender's requirements and the consultant's own authorization terms. A complete letter typically identifies:
- The issuing environmental professional or firm
- The addressee(s) and original client
- The subject property address and the report's title and date
- The specific parties now authorized to rely on it
- The defined purpose (a named financing, acquisition, or ownership transfer)
The SBA's Appendix 5 form is a useful concrete example of how detailed these letters can get. It requires letterhead and date, borrower and property identification, report and addenda references, an environmental professional's qualification statement, express reliance authorization, insurance evidence, and required signatures. Notably, it states that giving the borrower a copy is for information purposes only; it is not an update or modification of the investigation.
Insurance, Scope, and Execution Details
Some relying parties want proof of coverage before signing off. SBA's own form requires errors-and-omissions insurance of at least $1,000,000 per claim or occurrence as of the investigation date. That's an SBA-specific figure, not a universal coverage standard . Always verify what your particular lender or program actually requires.
Beyond insurance, a well-constructed letter also covers:
- Scope by reference to the report and applicable ASTM standard, without implying the letter itself expanded the original investigation
- Limitations and duration, including assumptions, exclusions, and any conditions on how long reliance remains valid
- Execution mechanics: consultant letterhead where required, proper signatures, and confirmation that no required program language was altered
What a Reliance Letter Does Not Do
A reliance letter is an authorization document, not an investigation. It does not replace the Phase I report — it only extends who can use one.
It does not independently examine:
- Soil or groundwater conditions
- Vapor intrusion pathways
- Buildings or historical property uses
- Adjoining properties
It also does not:
- Certify the property is free of contamination
- Eliminate environmental liability for any relying party
- Guarantee a CERCLA bona fide prospective purchaser defense
- Confirm a lender's underwriting requirements have been met
When an Update Is Needed Instead
Under the AAI rule, the report's cover date is generally not the same as the date its components were completed. That distinction can determine whether a report still qualifies.
| Timing window | Requirement |
|---|---|
| Within 180 days before acquisition | Five specific components — interviews, lien search, government records review, site visits, and professional declaration — must be conducted or updated |
| Within one year before acquisition | Prior information may qualify if those same five components were refreshed within the 180-day window |
| Materially changed conditions | Prior information must still reflect current, accurate site knowledge regardless of dates |
A reliance letter can't fix an expired timing window or stale information. If conditions have changed, or the report falls outside these windows, the fix is an update or new assessment from the environmental professional — not a signature on a letter.
Relying parties may still need their own user inquiries: title or lien checks, engineering-control review, and disclosure of relevant knowledge they hold. A letter does not relieve them of those obligations.
Outcomes also depend on the letter's exact wording, the underlying agreement, and applicable state law. Transaction-specific legal review is worth the time before you rely on one.
Timing, Cost, and Transaction Risks
There's no standardized fee or turnaround time for reliance letters. Pricing depends on several variables:
- Report complexity and age
- Number of parties needing authorization
- Liability language and insurance documentation requested
- Turnaround urgency
Treat any flat quote as a starting point for negotiation, not an industry benchmark.
The practical sequence usually looks like this:
- Identify every party who needs to be named, including lenders, borrowers, and assignees
- Locate the final report and verify its age and scope still meet lender requirements
- Submit the request to the original consultant with parties and preferred language
- Obtain original-client authorization if the engagement requires it
- Allow time for the consultant to review, negotiate terms, and execute
Common transaction risks come from rushing this process:
- Late requests that surface permission problems right before closing
- Omitted borrowers or lenders who assumed they were covered
- Expired reports outside the applicable timing window
- Altered program forms that no longer match lender requirements
- Reliance granted to the wrong legal entity
Request the letter early enough that the consultant, lender, and counsel all have room to resolve language issues before you're staring down a closing date.
How to Review a Reliance Letter Before Using It
Before treating a reliance letter as settled, run through a short checklist:
- Names match exactly — borrower, lender, purchaser, and property address align with transaction documents
- Report cross-check — the letter's scope, conclusions, and exclusions match the actual Phase I report and engagement agreement
- Reliance vs. distribution — confirm the document actually grants reliance, not just permission to receive a copy
- Program compliance — insurance evidence, signatures, letterhead, and governing law match current SBA or lender template instructions
If anything looks inconsistent, escalate to the original environmental professional, environmental counsel, or lender counsel. A reliance letter supports the Phase I findings; it does not replace them.
For landowners and agricultural stakeholders, a Phase I report and its reliance documentation settle historical liability questions. They do not tell you how to structure tenancy, revenue streams, or conservation practices going forward. Once due diligence is clear, that next planning conversation looks at the property's opportunities and constraints for long-term land use.
Frequently Asked Questions
How much does a Phase 1 assessment cost?
Pricing varies by property size, location, historical use, records complexity, and consultant scope. A reliance letter fee is typically separate from the assessment fee — get a site-specific quote rather than relying on general figures.
What triggers a Phase 1 ESA?
Common triggers include purchasing, refinancing, selling, or developing commercial or higher-risk property. Lender, investor, or CERCLA due diligence requirements often determine the required scope.
How long does it take to get a Phase 1 environmental assessment?
Turnaround depends on property complexity, records availability, site access, and consultant workload. Getting a subsequent reliance letter issued is typically a separate, shorter timeline from the assessment itself.
What is a Phase 1 reliance letter?
A Phase 1 reliance letter is a document from the original environmental professional that authorizes specifically named third parties to rely on an existing Phase 1 report. It does not replace or update the underlying investigation.
How long is a Phase 1 report good for?
Under ASTM practice, key components are generally treated as current for about 180 days, and reports older than one year usually need updating. Confirm current EPA, ASTM, SBA, and lender rules, and whether site conditions have changed, before relying on an older report.
