One organization sets the dates nearly every NYC independent school notifies you on. Here's what it actually controls, the official 2027–28 dates, and the part most admissions guides get wrong about Montessori: the real entry point isn't kindergarten.
If you're applying to private preschools or independent schools in New York, you'll meet the acronym ISAAGNY — the Independent Schools Admissions Association of Greater New York, a consortium of member schools that has coordinated admissions procedures since 1965. Its calendar is why acceptance emails across dozens of unrelated schools all land in the same late-February window. But ISAAGNY is narrower than parents assume, and for Montessori families the calendar carries a quirk that changes when you should start.
ISAAGNY coordinates notification and reply dates: the earliest moment member schools may tell you a decision, and the latest moment you must answer. That's it. It is, by its own description, not a regulatory organization — each member school remains responsible for its own admissions policies and outcomes. In particular, ISAAGNY does not set application deadlines. Those belong to each school, they vary widely, and they are the dates that actually bind you (more below).
For applications completed by Friday, January 8, 2027, ISAAGNY's published schedule for entry in September 2027 (checked against isaagny.org on August 18, 2026):
Preschool: decisions no earlier than 8:00 a.m. on Thursday, February 25, 2027; parent reply due by noon on Thursday, March 4.
Kindergarten: decisions no earlier than 10:00 a.m. on Thursday, February 4; reply by noon on Thursday, February 11.
Grades 1–8: decisions no earlier than 4:00 p.m. on Wednesday, February 10; reply by noon on Friday, February 26.
Notice the order: kindergarten families hear first, elementary families next, and preschool families — the majority of Montessori applicants — hear last, with the shortest reply window of the season: one week. If you're weighing a Montessori place against a seat elsewhere, that first week of March is when every decision converges. It's worth thinking through your ranking before the letters arrive, not after.
There is also an opt-in early round. Under it, participating schools may notify families from noon on Wednesday, December 9, 2026, with replies due by noon on Wednesday, December 16. Schools use this differently — some reserve it for sibling applicants (West Side Montessori, for example, tells sibling families electing an early decision that they'll hear on December 16), others for families ready to commit early. If a December answer would change your plans, ask each school whether it participates and on what terms; it's a school-by-school choice, not a blanket policy.
The January 8 “completed by” date describes when your file must be finished for the standard notification round — it is not permission to apply in January. Real deadlines run months earlier, and this fall's postings among the schools in our directory show the spread: The Montessori Schools (Flatiron & SoHo) opened applications in August, with early-decision visit appointments to complete by dates in October and November; Resurrection Episcopal Day School opens its application after Labor Day and closes it November 15, with a required open house before anything else; West Side Montessori opens September 1 and closes December 15. Three Montessori schools, three different deadlines — none of them in January. Treat each school's own posted date as the real one, and remember that popular toddler programs can also fill visit slots well before the paper deadline.
Most NYC admissions guides are written around the kindergarten cycle: apply the fall your child is 4, start at 5. Montessori runs on a different clock. The core offering is the Primary (3–6) classroom — a deliberate three-year arc in one mixed-age room, with the kindergarten year as its capstone. Schools therefore admit overwhelmingly at the bottom of the cycle: the twos and young threes. By age 4 or 5, most rooms are already full of children who started earlier, and open seats are scarce.
Two practical consequences. First, the application fall comes early: for September 2027 entry, West Side Montessori's Twos applicants must be born between December 1, 2024 and September 1, 2025 — meaning families are applying for children who are barely 2, sometimes younger for infant-toddler programs. REDS likewise warns applicants to read its age cutoffs carefully before starting the application. Second, entering at kindergarten age at a Montessori school is the exception, not the plan — where seats exist at all, they're usually vacancies rather than an entry class. If Montessori is on your list, the season to act is the one when your child is 1 or 2. If you're reading this with a 4-year-old, don't despair — ask specific schools about openings — but know you're shopping the leftovers, not the main intake.
August: build the shortlist — the directory shows every school's programs, price and transparency record side by side. September: applications open (many in the first week); book required open houses and info sessions now, since several schools gate the rest of the process behind them. October–November: tour season — go in with questions prepared, and watch for early-decision visit cutoffs. November–December: the first hard deadlines land (REDS November 15; West Side December 15); the Early Notification round pays out December 9–16. January 8: ISAAGNY completion date for the standard round; financial-aid deadlines cluster here too. February: decisions — K first (Feb 4), grades 1–8 next (Feb 10), preschool last (Feb 25). March 4, noon: preschool replies due.
None of this applies to the city's 3-K and Pre-K for All seats, including the public Montessori options — those run on the DOE's MySchools application windows, typically opening in winter with offers in late spring, plus the new 2-K round. If you're pursuing a free seat alongside private applications, you're managing two unrelated calendars; our free pre-K guide covers the public one.