Due Diligence on an Assumed Commercial Lease
When you take over someone else’s lease, you inherit their obligations as-is. Here is the order to investigate what you are stepping into before you close.
Last reviewed: May 26, 2026 by the BizLeaseCheck Editorial Team
General information, not legal advice.
Overview
Assuming a commercial lease — by assignment, as part of buying a business, or via sublease — means stepping into a contract you did not negotiate. You inherit its remaining term, its rent and pass-throughs, its restrictions, and often its liabilities and any existing defaults.
Do diligence in this order: confirm the remaining term and what consent the transfer needs, then read what you are assuming (rent, CAM, restrictions, surrender obligations), then verify the current status through an estoppel certificate, and finally lock down protections (a release for the seller, deposit transfer, and landlord sign-off) before closing.
Topics to check
Start with how much lease you are inheriting — the remaining term and any renewal options — and the structure of the deal: a true assignment (you take the original tenant’s place and gain privity of estate with the landlord), a sublease (you answer to the original tenant, not the landlord), or assumption through a business purchase. Each carries different rights and risk.
Then find the lease’s assignment clause: almost every commercial lease requires the landlord’s consent to transfer, and the terms of that consent (and the landlord’s alternatives) can make or break the deal.
Assignment (Cornell LII Wex)Work through the economic and operational terms you will inherit: base rent and escalations, percentage rent, operating-expense/CAM pass-throughs (and any year-end true-up for periods before you took over), the use clause and exclusives, surrender and restoration obligations, and repair and maintenance duties for things like the roof and HVAC.
You are buying these obligations, so price them. A below-market rent can be offset by an inherited restoration obligation or an uncapped CAM exposure.
Get a landlord estoppel certificate to confirm the current rent, the security deposit, the absence of defaults, and any side agreements — and compare it to the lease. Confirm the security deposit actually transfers, get a release or novation so the seller’s (and your) liability is clear, and obtain the landlord’s written consent before you close.
The diligence is only useful if you turn it into closing conditions: no consent, no clean estoppel, no deal.
Estoppel (Cornell LII Wex)Key takeaways
- Assuming a lease means inheriting its obligations and often its liabilities as-is.
- Confirm the remaining term, the transfer structure, and the landlord-consent terms first.
- Price the inherited rent, CAM/true-up exposure, use restrictions, and surrender obligations.
- Get an estoppel certificate to verify rent, deposit, defaults, and side agreements.
- Turn diligence into closing conditions: landlord consent, clean estoppel, deposit transfer, and a release.
Official resources
Legal-review notes
Guide confidence marker: Medium confidence.
- Assignment, consent, and inherited-liability rules depend on the lease wording and state law; confirm with counsel.
- This guide is general issue-spotting, not jurisdiction-specific legal advice.
Frequently asked questions
What does it mean to assume a commercial lease?
It means taking over an existing lease — through an assignment, a business or asset purchase, or a sublease — so you step into the remaining term and its obligations. You generally inherit the lease as-is, including its rent, restrictions, and often its liabilities, which is why due diligence matters.
What is the single most important diligence document?
The landlord estoppel certificate. It confirms the current rent, the security deposit on hand, whether there are any defaults or unpaid amounts, and any side agreements — letting you verify the lease before you inherit it and catch problems the seller might not disclose.
Is this legal advice?
No. This is general information. Lease assignment, consent, and liability rules depend on the exact lease and your state, so have a qualified attorney review the lease, the assignment documents, and the landlord consent before you close.