What is the difference between an amendment and an addendum?

An amendment changes a term that is already in the lease (the rent amount, the end date, who is on the lease). An addendum adds something the lease did not cover (a pet policy, a parking space, a lead-paint disclosure). In practice both are signed attachments that become part of the lease, but the labels help everyone understand whether a term is being changed or added.

Can a landlord change a fixed-term lease in the middle?

Generally no, not without the tenant agreeing. A signed fixed-term lease locks the terms for the term. A landlord cannot unilaterally raise the rent or add a fee mid-term. Both sides have to sign an amendment. The exception is a month-to-month tenancy, where either party can change terms with the required statutory notice.

Does a lease change have to be in writing?

It should be, every time. Most leases include an entire-agreement clause stating that only written, signed changes count, which makes a verbal deal worth nothing in a dispute. Even where an oral change might technically be enforceable, proving it is nearly impossible. Put every change in a signed amendment or addendum.

Do all tenants have to sign an amendment?

Yes. If the lease has multiple tenants or a co-signer, everyone who signed the original lease should sign the change. A change signed by only one of several tenants can be challenged by the others as not binding on them.

Can I just write the change on the original lease by hand?

You can initial a small correction before signing, but changing a lease after it is signed is cleaner as a separate dated document that references the original lease, states exactly what is changing, and is signed by all parties. Handwritten edits on an executed lease invite disputes about who wrote what and when.

Lease Amendments and Addendums: How to Change a Signed Lease

Once a lease is signed, neither side gets to rewrite it alone. Adding a roommate, changing the rent, allowing a pet, or moving the end date all require the right document signed by the right people. Done properly, a change is airtight. Done casually, by text or by crossing out a line, it becomes the thing both sides argue about later.

Amendment vs addendum

The two words get used loosely, but the distinction is simple:

Amendment. Changes a term already in the lease. Examples: the monthly rent, the lease end date, the names on the lease.
Addendum. Adds a term the lease did not address. Examples: a pet policy, a parking-space assignment, a smoking ban, a required disclosure.

Both become part of the lease once signed, and both are governed by the same core rule: all parties have to agree.

The rule that surprises people: you cannot change a fixed-term lease alone

A signed fixed-term lease locks the terms for the whole term. A landlord cannot raise the rent, add a fee, or impose a new rule mid-term without the tenant's agreement, and a tenant cannot drop a term they no longer like. Any mid-term change needs an amendment both sides sign. The major exception is a month-to-month tenancy, where either party can change terms going forward with the notice your state requires.

What a clean amendment or addendum includes

A reference to the original lease (the property address and the lease date)
The names of all parties to the lease
Exactly what is changing or being added, in plain language
The effective date of the change
A line confirming all other lease terms stay in force
Signatures and dates from every tenant, co-signer, and the landlord

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Common changes and how to handle each

Rent change mid-term. Needs a signed amendment in a fixed-term lease. In month-to-month, give the required notice instead.
Adding or removing a roommate. Often handled as an amendment plus screening; see our guide on adding a roommate mid-lease.
Allowing a pet. A pet addendum that sets the rules, any pet rent or deposit, and the consequences for violations.
Extending the term. An amendment moving the end date, or a full renewal; see lease renewal vs new lease vs month-to-month.
Required disclosures. Lead paint, mold, and similar items are added as addendums to the lease packet.

When a new lease beats an amendment

Small changes are best as a one-page amendment. But when several major terms change at once (new rent, new term, new occupants), a fresh lease is cleaner than stacking amendments on top of an old document. A pile of amendments gets confusing and increases the odds that two clauses contradict each other.

Mistakes that void a change

Only one of several tenants signs
The change is verbal or by text, with no signed document
Handwritten edits on the original lease with no initials or date
A landlord imposing a mid-term change unilaterally in a fixed-term lease
Skipping the statutory notice for a month-to-month change

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