Lease Critical Dates

The defect

Renewal and termination options are almost always stored as a deadline — one date, before which notice must be given. Real clauses are usually a window:

> Tenant shall give notice **not less than one hundred eighty (180) nor more than two hundred > seventy (270) days** prior to the Expiration Date.

Notice on day 300 is as invalid as notice on day 100. A deadline-only model reports that you are eleven months early and therefore fine — and the notice sent on that advice does not exercise the option. Nothing rejects it at the time. It sits in the file looking like compliance until the landlord says otherwise, by which point the window may have closed.

  evaluateOption(option, { now: "2026-06-01" });
  // { status: "too_early",
  //   detail: "the window does not open until 2027-04-05. Notice sent today would be invalid
  //            for being early — this is not the same as \"no action needed yet\"." }

too_early is a distinct status, deliberately. A UI that renders it and "not yet due" identically recreates the whole defect.

Which days count

180 days and 180 business days are different clauses — roughly six months versus nine. A test asserts the two bases produce dates more than sixty days apart, because that difference is the bug, not a rounding detail.

Business-day arithmetic needs a holiday calendar, and without one it is silently wrong near year-end. So:

  evaluateOption({ ...option, basis: "business" }, { now });
  // { precise: false, detail: "… NOTE: business days counted without a holiday calendar,
  //   so this is a weekends-only approximation and will be wrong across public holidays." }

It reports the approximation rather than presenting it as fact. Supply holidays and precise becomes true.

All arithmetic is UTC. A lease deadline is a calendar date, not an instant, and local-time arithmetic moves it by a day between a laptop and production.

The report keeps what lapsed

upcomingCriticalDates still returns missed options at critical urgency. An option that lapsed last month is not stale noise — it changes what the lease now is, and dropping it from the report is how nobody notices for a year.

Not legal advice

This computes dates from parameters you supply. Reading the clause is the actual work and it is a legal reading this package cannot do: whether the period runs from the Expiration Date or the Commencement Date, whether "days" means calendar or business days, whether notice is effective on dispatch or on receipt. Wrong inputs produce confident, precise, wrong dates.

| not included | why | |---|---| | Extracting terms from a lease document | clause-span-grounding verifies an extractor's output | | Sending or tracking notices | dates only | | Holiday calendars | jurisdiction-specific and they change; supply your own | | Rent, escalations, CAM | different problem entirely |