Most tenants sign an addendum without ever comparing it line-by-line to the lease they already signed. This segment sells that comparison, not legal protection. A side-by-side review of the original signed lease and the proposed addendum or amendment: what changes, what stays the same, the proposed effective date, whether the change adds a term or rewrites one, and the dollar effect totalled where the papers state figures. Send us the original signed lease and the proposed addendum together — one without the other cannot be checked.
The pack checklist for a mid-lease addendum / amendment review, in order. You need both documents — the original signed lease and the proposed addendum. The answers are in whether their wording agrees.
Lay the two papers side-by-side. List every term the addendum touches, every term it leaves alone, and the proposed effective date exactly as written. A change with no stated effective date, or a date before the presentation date, is flagged as a question — never assumed.
Check whether the change is framed as an addition (an addendum — a new term added) or a modification or deletion of an existing term (an amendment). The two are not interchangeable, and the label alone does not decide the effect: check what the document actually does to each original clause it names.
Sources checked for this segment agree an amendment or addendum generally must be signed by all parties to become binding, and a tenancy can normally only be changed if both parties agree. Check the signature lines on their face: who is asked to sign, whether every party on the original lease has a line, and any signing deadline stated. Whether a signature is required in your exact situation is never determined here.
Find the term type in the original lease. As a question shape only: California month-to-month terms can be changed with proper notice in a way fixed-term terms generally cannot mid-term. California mechanics are never generalised to other states, and which situation you are in is flagged as a question, never as a determination for you.
A change that raises rent, shifts a responsibility such as utilities from landlord-paid to tenant-paid, or alters the term itself is a major change, not a routine policy note. Where the papers state figures, the review totals the dollar effect over the months remaining — the worked example in section 2 shows the arithmetic in full.
Check whether the addendum says it controls over the lease if the two conflict, whether the original lease requires changes to be in a signed writing, and whether any original clause is deleted without being named. Sources note a signed addendum can still be unenforceable if it conflicts with applicable law — that possibility is presented only as a seek-counsel-promptly pointer, never as a ruling on your papers.
This example is a clearly labelled hypothetical, with invented figures and dates. It shows how a money change is totalled over the months remaining — it is not a real tenant’s papers, and it proves nothing about any real lease or any real addendum:
Treat each point below as a “check whether…” question, never as a conclusion about papers you have not read in full:
Check whether the original lease and the proposed addendum, on their face, require a signed writing by all parties for a change — as a question to confirm, never as a ruling on whether your signature is required.
Check whether the original lease states a fixed term or a month-to-month tenancy, and check that wording against the change proposed. As an example only: California has its own rental rules that do not apply in other states, and a city rule can be stricter.
Check whether the change raises rent, shifts a paid responsibility, or alters the term, and — where the papers state figures — check whether the total over the months remaining matches the monthly figure multiplied out in full.
Check whether any addendum wording conflicts with the original lease, deletes a clause without naming it, or claims to control over the lease — flagged as questions to confirm in writing, with any possible conflict with applicable law pointed to a local tenant attorney or legal aid promptly.
Copy these into an email or portal message so the answers are in writing. Calm and factual — no threats, no demand-letter language. Ask before signing, in your own name.
Send us the original signed lease and the proposed addendum together — get what changes flagged clause by clause, addition vs. modification sorted, signature and term-type wording surfaced, and any stated dollar effect totalled in plain numbers for $9. No enforceability determination, no outcome promise, no refusal or counter-addendum drafted for sending, no demand letter, no negotiation, and no filing service.
LeaseLens is not a law firm and this is not legal advice. Reports are plain-English risk flags from a concierge review, not a legal ruling on your lease, your addendum, or whether you must sign.
Start a review →No. LeaseLens never determines whether a specific addendum is enforceable, whether a signature is required in your exact situation, or whether a clause conflicts with state or local law. It compares the two papers, totals stated figures, and frames the rest as questions. A signed addendum can still raise enforceability questions if it conflicts with applicable law — take that possibility to a local tenant attorney or legal aid promptly.
Send the original signed lease and the proposed addendum or amendment together, including the proposed effective date and any signature or deadline page exactly as presented. One document without the other cannot be checked: the lease alone cannot show what the new paper changes, and the addendum alone cannot show what it replaces or deletes.
As the papers generally use the words, an addendum adds a term and an amendment modifies or deletes an existing term — the two are not interchangeable. The label alone does not decide the effect: check what the document actually does to each original clause, whether it says it controls over the lease, and whether it is signed by all parties.