A commencement date agreement fixes the one date every other deadline is measured from, and it is usually a separate one-page letter signed months after the lease. Upload the lease and the commencement date agreement together and get the commencement date, the rent commencement date, the expiration date, the term length, and every option and notice deadline that counts off from them pulled into structured fields, each citing its source page.
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Almost every deadline in a commercial lease is written as an interval from the commencement date, not as a fixed date. When the actual commencement slips from the lease-signing estimate, which it usually does, every downstream date moves with it. A commencement date agreement is the document that confirms the real date, and if it is filed separately from the lease the whole schedule silently drifts. Each row names a field, says what it sets, and states what breaks when it is wrong.
| Commencement field | What it sets | What breaks when it is wrong |
|---|---|---|
| Commencement date | The date the lease term legally begins, often the date the landlord delivers possession, not the lease signing date | Every option, notice, and expiration date is measured from here, so an estimated date left in the record throws off the entire critical-date calendar |
| Rent commencement date | The date rent actually starts, frequently later than the commencement date because of a free-rent or buildout period | The rent roll bills too early or too late, and the free-rent concession is either lost or overpaid |
| Expiration date | The last day of the term, computed as commencement plus the term length | A wrong expiration date means the renewal notice window, itself keyed to expiration, is calculated against the wrong deadline |
| Term length and any partial month | The stated number of years and how a partial first month is handled | A term measured from the wrong start produces the wrong expiration and the wrong number of escalation anniversaries |
| Delivery and possession condition | Whether commencement was triggered by delivery, substantial completion of landlord work, or a fixed outside date | If commencement was tied to a condition that was disputed, the confirmed date in the agreement resolves it, and missing that resolution reopens the argument |
| Option and notice deadlines keyed to commencement | Renewal, expansion, and termination windows written as intervals from commencement or expiration | The single most expensive miss: a renewal deadline counted from an estimated commencement date can be off by months |
| Escalation anniversary | The annual date rent steps up, usually the commencement or rent-commencement anniversary | Escalations applied on the wrong anniversary compound the rent error across the entire term |
The job is to read the lease and the commencement date agreement together, replace every estimated date in the lease with the confirmed date, and recompute the downstream deadlines that count off from it.
The actual commencement date from the executed agreement, not the estimate written into the lease at signing, so the whole schedule starts from the right day.
The date rent actually begins, captured separately from commencement so any free-rent or buildout gap is preserved and the roll bills on the correct date.
The expiration date recalculated as the confirmed commencement plus the term, so the renewal window that keys off expiration lands on the right deadline.
The commencement date agreement matched back to its lease by parties and premises, so a letter filed on its own is not lost from the abstract.
Every option, notice, and termination window written as an interval from commencement or expiration, converted into real calendar dates off the confirmed start.
The annual step-up date tied to the confirmed commencement or rent-commencement anniversary, so escalations apply on the right day for the whole term.
From a lease plus its commencement date agreement to one record where every deadline is measured from the confirmed date, with a source citation per field.
Include the original lease with its estimated dates and the executed commencement or delivery letter that confirms them. Scans are fine.
The model returns the confirmed commencement date, rent commencement date, expiration, term, and every deadline keyed to them, replacing the lease estimates with the confirmed figures.
Each field links to its source page. The output flags where the confirmed date differs from the lease estimate so you can see exactly what moved.
Push the confirmed commencement, rent commencement, expiration, and option deadlines to Excel, CSV, JSON, or the API so the critical-date calendar reflects reality.
Last updated July 2026. What a commencement date agreement is, why the commencement date differs from the signing date, and how a confirmed date resets every downstream deadline.
A commencement date agreement is a short document, often a single-page letter, that the landlord and tenant sign after the lease to confirm the actual date the term began, the rent commencement date, and the expiration date. It exists because the lease is signed before the space is ready, so the lease can only estimate when the term will start. Once the landlord delivers possession or finishes its work, the parties execute the commencement date agreement to lock the real dates in. Abstracting it means pulling those confirmed dates into the record and recomputing every deadline that counts off from them. The confirmed dates feed the calendar handled by critical date extraction and slot into the full field set on the commercial lease abstract template.
The commencement date is different from the signing date because a commercial lease is usually signed months before the tenant can occupy the space, while the landlord builds out improvements or the existing tenant vacates. The term does not start at signing; it starts when the lease says it does, most often on delivery of possession or substantial completion of the landlord's work. That gap is why the lease can only estimate commencement, and why a separate agreement is needed to confirm the real date once it is known.
The commencement date is when the lease term legally begins; the rent commencement date is when the tenant actually starts paying rent, and it is frequently later because of a free-rent or buildout period. A lease might commence on March 1 but abate rent for three months, so rent commences June 1. Both dates matter: the term and expiration count from commencement, while billing counts from rent commencement. The two are covered in depth on the guide to lease commencement date vs rent commencement date.
If the commencement date agreement is never signed, the lease dates stay estimates and the parties can end up disputing when the term actually started, which affects the expiration date, the renewal window, and how much rent was owed. Many leases include a fallback that sets commencement by a formula if no agreement is executed, but that formula still has to be applied to the facts. The practical fix is to abstract whatever confirms the date, whether a signed agreement, a delivery notice, or an estoppel certificate, and put the resulting deadlines on a monitored calendar.
The commencement date sets the expiration date, and most renewal and option deadlines are written as an interval before expiration, so a wrong commencement date pushes every one of those deadlines to the wrong day. A renewal notice due "nine months before expiration" is only as accurate as the expiration date it is measured against, and expiration is only as accurate as commencement. That chain is why confirming commencement is the first step to a reliable critical-date calendar, and why the option deadlines it drives belong on the workflow covered by lease renewal abstraction.
Yes, and the portfolio is where estimated dates do the most damage, because a lease that commenced two years ago on an estimate never gets corrected until a deadline is missed. The model reads each lease and its commencement date agreement, returns the confirmed commencement, rent commencement, expiration, and term as structured fields, and recomputes the deadlines keyed to them. Accuracy depends on scan quality, and every published accuracy figure in this category is self-reported, so test on your own worst-scanned lease first. The general tool is on lease abstraction software.
Still have questions? Our team is happy to help.
Talk to our teamA short document, often a one-page letter, that the landlord and tenant sign after the lease to confirm the actual commencement date, rent commencement date, and expiration. It exists because the lease is signed before the space is ready and can only estimate when the term starts.
A commercial lease is usually signed months before occupancy while the landlord builds out the space. The term starts when the lease says, most often on delivery of possession, not at signing, so the confirmed date needs a separate agreement.
The commencement date is when the term legally begins; the rent commencement date is when the tenant starts paying, often later because of a free-rent period. The term counts from commencement, while billing counts from rent commencement.
The lease dates stay estimates and the parties can dispute when the term started. Many leases include a fallback formula, but the practical fix is to abstract whatever confirms the date, a delivery notice or estoppel, and calendar the resulting deadlines.
It sets the expiration date, and most renewal deadlines are an interval before expiration, so a wrong commencement date pushes every option deadline to the wrong day. Confirming commencement is the first step to a reliable critical-date calendar.
Yes. The model reads each lease and its commencement date agreement, returns the confirmed commencement, rent commencement, expiration, and term as structured fields, and recomputes the deadlines keyed to them, source-linked per field.
Put every deadline keyed to commencement on the calendar.
Learn moreThe renewal deadlines that count off from expiration.
Learn moreThe full field list the confirmed dates slot into.
Learn moreThe document that later modifies the term or dates.
Learn moreManage critical dates across the portfolio.
Learn moreThe full overview of our AI lease abstraction tool.
Learn more