Lease Assignment vs Sublease

A lease assignment transfers the entire remaining lease, and all liability for rent and terms, to a new tenant; a sublease is a new lease between the original tenant and a subtenant, leaving the original tenant liable to the landlord—making assignment riskier for the landlord but often requiring explicit consent.

The legal distinction: privity of contract

The fundamental difference between an assignment and a sublease is the chain of contractual liability:

In an assignment, the original tenant exits the lease entirely, and the new tenant steps directly into the original lease agreement with the landlord. The new tenant becomes the “assignee” and enters into privity of contract with the landlord. The original tenant is released from the lease and no longer owes rent. The landlord’s recourse for non-payment or breach goes directly to the new tenant.

In a sublease, the original tenant remains the “head lessee” (the party bound to the landlord under the original lease) and becomes a “sublessor” who leases the space to a subtenant under a separate, shorter lease. The subtenant owes rent to the head lessee, not to the landlord. If the subtenant fails to pay, the head lessee must pay the landlord in full, then pursue the subtenant for recovery. The landlord’s only direct recourse is the original tenant.

In legal terms, a sublease creates a new chain—landlord–original tenant–subtenant—whereas an assignment creates a direct landlord–new tenant relationship.

Landlord consent and approval

This distinction directly affects landlord consent requirements:

Assignment consent is typically explicit and discretionary. Most commercial leases require the landlord’s written approval before an assignment, and many leases allow the landlord to refuse consent on any grounds (or to “approve or withhold consent in landlord’s sole discretion”). Some jurisdictions (notably California) impose a “reasonableness” standard, preventing landlords from arbitrarily withholding consent. Landlords may demand a surety or corporate guarantee from the new tenant, or negotiate a profit-sharing clause if the new tenant subleases at a higher rate.

Sublease consent is often more lenient. Some leases permit subleasing without landlord approval, or require only notice. Others require approval but are more easily granted, because the landlord retains the original tenant as a security blanket—if the subtenant fails, the original tenant is still liable. Some landlords impose a “recapture right,” allowing them to retake the space if the tenant proposes a sublease above a certain rent threshold.

This difference makes subleasing attractive to tenants who want flexibility without surrendering the lease entirely.

Risk allocation and the landlord’s preference

From a landlord’s perspective, an assignment is cleaner but subleases offer more security:

Assignment advantages for landlord:

• Direct contractual relationship with the new tenant (no intermediary liability).
• Can evaluate the new tenant’s creditworthiness before approving.
• If the new tenant defaults, the landlord has direct legal recourse.
• Simplifies accounting and lease administration.

Assignment disadvantages for landlord:

• The original tenant is released and no longer guarantees performance.
• If the new tenant is weaker financially, the landlord has lost a credit-worthy obligor.
• The landlord must review and approve the assignment, incurring legal and transaction costs.

Sublease advantages for landlord:

• The original tenant remains liable as a guarantor; if the subtenant fails, the original tenant is on the hook.
• The landlord can monitor occupancy and rent flows from the original tenant.
• The landlord may capture upside if the subtenant pays the original tenant above the head lease rate.

Sublease disadvantages for landlord:

• Indirect relationship with the actual occupant; less control over the space and its use.
• If the original tenant becomes insolvent, the landlord loses the revenue stream from the sublease.
• More complex enforcement—must pursue the original tenant first, then the original tenant must pursue the subtenant.

For these reasons, landlords often prefer subleases and may refuse assignments altogether unless certain conditions are met.

Practical use cases

Assignment is common when:

• A tenant’s business needs change, and they want to exit the lease entirely (e.g., a company relocates or downsizes).
• A new, creditworthy tenant is available to take over the space on the same terms.
• The tenant wants a clean break and is willing to invest time in landlord approval.
• Market rents have risen, and the assignment price (a one-time payment from the new tenant to the exiting tenant) justifies the effort.

Sublease is common when:

• A tenant has excess space temporarily and wants to recoup rent while preserving the option to reclaim the space.
• A tenant plans to return to occupying the full space within 1–3 years (e.g., after a corporate restructuring).
• Market conditions are soft, and the landlord might not approve an assignment to a weaker tenant.
• The original tenant wants passive income without relinquishing the lease.
• The subtenant’s need is short-term (e.g., a startup needing 18 months of space during a growth phase).

Financial implications: assignment profit and sublease economics

In a rising market, the difference between assignment and sublease creates a wealth transfer opportunity.

If a tenant holds a lease at $25/sq. ft. and market rents rise to $35/sq. ft., the tenant has accrued $10/sq. ft. of “assignment value” (the difference between head lease rent and market rent).

In an assignment, the original tenant can negotiate an “assignment premium”—the new tenant pays the original tenant a one-time lump sum for the right to assume the below-market lease. For example, on a 5-year remaining lease for 5,000 sq. ft., the premium might be $25/sq. ft. × 5 years × 5,000 sq. ft. = $625,000. The original tenant captures this value in full.

In a sublease, the original tenant captures value more slowly. They sublet the space at market rate ($35/sq. ft.) but pay the landlord at the head lease rate ($25/sq. ft.), pocketing a $10/sq. ft. margin. Over a 5-year sublease, that’s $10 × 5 × 5,000 = $250,000 in gross profit (less the tenant’s costs). The value is distributed over time, not captured upfront.

This is why tenants with valuable below-market leases prefer assignments; they can monetize the lease in one transaction.

Accounting for assignments and subleases

Under IFRS 16 and ASC 842 (the lease accounting standards), both assignments and subleases have specific treatment:

• An assignment is recorded as a lease termination for the original tenant; if the assignment generates a gain (e.g., an assignment premium), it is recognized when the assignment is complete.
• A sublease is recorded as the original tenant creating a new operating lease with the subtenant while remaining liable under the head lease. The subtenant’s rent reduces the original tenant’s net lease expense.

Landlords must track the identity of their actual occupant in a sublease, because accounting and revenue recognition require clarity on who owes rent.

Restrictions and approval tactics

Tenants seeking to assign or sublease should anticipate:

• Profit-sharing clauses: The landlord captures a percentage of any assignment premium or sublease margin above the head lease rate.
• Recapture rights: The landlord can retake the space if the tenant proposes a sublease at a rate above a threshold or if the subtenant is in a competing industry.
• Credit review: The landlord may demand financial statements and credit references for both the assignee and subtenant.
• Lease amendment: The landlord may require the assignee to sign a new lease or lease assumption, resetting term clocks for renewal and option pricing.

Savvy landlords often encourage subleasing over assignment, because the original tenant remains their credit anchor.

See also