New York Mechanics Lien Deadline Calculator, and the Day 35 Trap
New York puts three different filing windows in a single subdivision of Lien Law section 10, and then hides the deadline that actually kills liens in the next section. Section 10(1) gives you eight months from the last item of work or materials, four if there is a single family dwelling on the property, and ninety days if what you are liening is retainage. Get that right and you are halfway there. Section 11 then gives you thirty days after filing to serve a copy on the owner, and a separate thirty-five days to file the proof of that service with the same county clerk, and it is the thirty-five day one that says failure shall terminate the notice as a lien. Put your dates in and the page lays out all of it, filing, service, proof of service, and the day one year later when the lien dies on its own.
Worked example
These are the figures the calculator opens with and the answer it gives. Change anything above and every number below moves with it.
- What the date below isMy last day of work or delivery
- Day of the month12
- MonthMarch
- Year of that month2026
- What is on the propertyNot a single family dwelling
- Days early you want to be at the clerk10 days
Last day to file the notice of lienNovember 12, 2026
Serving the owner is not what keeps the lien alive. Section 11 gives you thirty days after filing to serve the copy, and then a separate thirty-five days to file the PROOF of that service with the same county clerk. The words are that failure to do it within thirty-five days shall terminate the notice as a lien. No motion, no hearing, no cure. Serve on day 29 and forget the affidavit and you have a filed document with no lien behind it.
If there is a single family dwelling on this property, this answer is four months too long. Section 10 cuts the window in half for one, and the same job would have expired on July 13, 2026. Being wrong in that direction is the expensive one, so settle what is on the ground before you diary this date.
Filing is the middle of this, not the end. Section 17 gives the lien one year from the day it is filed and then it is gone, unless inside that year you either commence a foreclosure action AND file a notice of pendency with the same county clerk, or file an extension at the county clerk, which buys one more year and only one. A lien nobody renewed is not a lien you can still enforce.
This is the private property clock. If this is a school, a road, a housing authority or anything else built for the state or a public corporation, section 12 governs instead: before completion and acceptance, and within thirty days after, filed with the head of the department or bureau in charge and with the comptroller. Filing that one with a county clerk does nothing at all.
| Your rule | eight months, everything else10(1), the general window, counted from the last item of work or materials |
|---|---|
| Counted from | March 12, 2026your last item of work performed or materials furnished |
| Target date | November 2, 202610 days in hand, moved back off a weekend because the counter is shut |
| Serve the owner by | December 2, 2026thirty days after you file, section 11, counted here off the target date |
| File proof of service by | December 7, 2026thirty-five days after you file, and this is the one that terminates the lien on its own |
| The lien expires | November 2, 2027one year from filing under section 17, unless you renewed it or sued and filed a notice of pendency |
| Renewing it | extension at the county clerkone year more, once, and after that only a court can continue it |
| What this clock counts | months, not days10(1) says months, so a job ending on the 31st and one ending on the 1st of the next month are five weeks apart on the calendar and one month apart here |
What this calculator assumes
- Section 10(1) counts months, not days, from the last item of work performed or materials furnished. Eight months from the 31st of a month lands on the last day of the target month when that month is shorter, which is how a month count has to work.
- Your last item is the last real item. Section 10 says the window dates from the last item of work performed or materials furnished, so a warranty visit, a punch list callback or a trip to fix your own defect is not a fresh start.
- The four month window belongs to a single family dwelling. Section 10 then carves out a dwelling in a filed subdivision still owned by the developer, which is not a single family dwelling for this purpose and gets the eight month window.
- The service dates below are counted from the day you actually walk into the clerk's office, not from your deadline. They are shown here off the target date so that the schedule is a real calendar rather than a set of offsets.
- A deadline landing on a Saturday or Sunday is moved to the next business day by General Construction Law 25-a. That section moves public holidays too, and the holiday list is General Construction Law 24, which is the clerk's calendar and not this page's.
- This is the private property clock. A lien on a public improvement runs under section 12, which is thirty days after completion and acceptance, filed with the head of the department and the comptroller rather than with a county clerk.
Three filing windows, and they live in one sentence
Section 10(1) reads as one long provision with two provisos bolted onto it, and each proviso is a different deadline. The base rule is that a notice of lien may be filed during the progress of the work, or within eight months after the completion of the contract, or the final performance of the work, or the final furnishing of the materials, dating from the last item of work performed or materials furnished.
The first proviso says that where the improvement is related to real property improved or to be improved with a single family dwelling, the same window is four months. The second says that where the notice of lien is for retainage, it may be filed within ninety days after the date the retainage was due to be released.
Those are not variations on one clock. The retainage window does not start on your last day on site at all, it starts on a date buried in your contract. So the first question this page asks is which of the three you are on, because the answer changes the starting event as well as the length.
Day 35 is the deadline that quietly kills New York liens
Section 11 has two deadlines in it and most people only remember the first. Within five days before or thirty days after filing the notice of lien, you have to serve a copy on the owner. That much is well known.
Then comes the sentence that does the damage: failure to file proof of such a service with the county clerk within thirty-five days after the notice of lien is filed shall terminate the notice as a lien. Not voidable, not defective, not subject to a motion. Terminated.
So there are two separate acts five days apart. Serving the owner is one. Walking the affidavit of service back into the same county clerk's office is the other, and it is the second one that has the automatic penalty attached to it. A contractor who serves the owner by certified mail on day 28, files the green card in a job folder and moves on has lost the lien without anybody telling them.
A single family dwelling changes three numbers, not one
Everybody knows the filing window drops from eight months to four. Fewer people notice what section 17 does at the other end. A lien normally lasts one year from filing and can be renewed by walking into the county clerk and filing an extension, which buys another year.
Section 17 takes that away for a single family dwelling. A lien on real property improved or to be improved with a single family dwelling may only be extended by an order of a court of record, or a judge or justice thereof. There is no counter option.
That means the same job, on a house instead of a warehouse, gives you half the time to file and no cheap way to keep the lien alive at the one year mark. If you are still unpaid eleven months later, the difference between those two properties is the difference between a filing fee and a lawyer.
The spec house exception that gives you eight months back
Section 10 does not leave single family dwelling undefined, and the definition is worth reading before you shorten your own deadline. The term does not include a dwelling unit which is part of a subdivision that has been filed with a municipality, when at the time the lien is filed the property is owned by the developer for purposes other than his personal residence.
Developer is defined in the same place as any private individual, partnership, trust or corporation which improves two or more parcels of real property with single family dwellings pursuant to a common scheme or plan.
Read together, a house in a builder's tract that the builder still owns is not a single family dwelling for section 10 purposes, and the window is eight months. That is an easy four months to give away by assuming that a house is a house. If the property is one of a row going up under one plan and the builder has not sold it yet, this is worth checking rather than assuming.
New York moves a deadline off a weekend, and plenty of states do not
General Construction Law section 25-a says that when any period of time, computed from a certain day, within which or after which or before which an act is authorized or required to be done, ends on a Saturday, Sunday or a public holiday, the act may be done on the next succeeding business day. The catchline says in statutes, which is what makes it reach a Lien Law period.
This page moves weekends for you. It does not move public holidays, because the holiday list is General Construction Law section 24 and the calendar that actually binds you is the one taped to the door of your county clerk's office.
It is worth knowing this is a New York feature and not a general rule. Florida chapter 713, to take the obvious comparison, contains nothing of the kind, so a Florida deadline landing on a Sunday is still a Sunday. Assuming a roll exists in a state that has not written one is a good way to be one day late.
Filing the lien is the middle of the job, not the end of it
Section 17 gives the lien one year from the day the notice of lien was filed. After that it is not a lien, whatever the county clerk's index still says.
You keep it alive one of two ways. Commence an action to foreclose and file a notice of pendency of that action with the same county clerk inside the year, which is the real route if you mean to collect. Or file an extension with the clerk inside the year, which continues the lien and redockets it, and which is available on everything except a single family dwelling.
An extension buys one more year and no lien can be continued by extension for more than a year from the filing of it. After that only a court order continues it, and a court order runs one year at a time for at most two successive years. The practical version is simple: a New York lien you filed and then ignored has a shelf life, and the shelf life is shorter than most disputes.
Questions people ask
How long do I have to file a mechanics lien in New York?
Eight months from the last item of work performed or materials furnished on most private jobs, under Lien Law 10(1). Four months if the property is improved or to be improved with a single family dwelling. Ninety days from the date the retainage was due to be released if what you are liening is retainage. You can also file at any time during the progress of the work, so nothing forces you to wait until the end.
What is the thirty-five day rule in New York Lien Law?
Section 11 says failure to file proof of service with the county clerk within thirty-five days after the notice of lien is filed shall terminate the notice as a lien. It is a separate deadline from the thirty days you have to serve the owner. Serving the owner and never filing the affidavit of service is enough to lose the lien on its own.
Do I serve the owner before or after filing the lien in New York?
Either. Section 11 allows service within five days before filing or thirty days after it. What is not optional is the proof: the affidavit of service has to reach the county clerk within thirty-five days of the filing whichever order you did it in.
Does a New York mechanics lien expire?
Yes. Section 17 gives it one year from the day it was filed. Inside that year you either commence a foreclosure action and file a notice of pendency with the same county clerk, or file an extension at the clerk, which continues it for one more year. On a single family dwelling the extension route is closed and only an order of a court of record will continue the lien.
Is a house always on the four month deadline in New York?
No. Section 10 excludes a dwelling in a subdivision filed with the municipality while it is still owned by the developer for a purpose other than living in it, and defines a developer as anyone improving two or more parcels with single family dwellings under a common scheme or plan. A spec house in a builder's tract is on the eight month clock.
What counts as the last item of work in New York?
The last real item of labor or materials that was part of the work. Section 10 dates the window from the last item of work performed or materials furnished, so a warranty callback, a punch list return or a trip to correct your own defect is not a new starting point. If your final furnishing date is arguable, the conservative date is the one to diary.
What if my New York lien deadline lands on a Saturday?
General Construction Law 25-a moves it to the next succeeding business day, and it does the same for a Sunday or a public holiday. This page moves weekends for you. It does not carry the public holiday list in General Construction Law 24, so check the county clerk's calendar for anything falling next to one.
Is the deadline different on a public job in New York?
Completely. A lien on a public improvement runs under Lien Law 12, which allows filing at any time before the construction or demolition is completed and accepted, and within thirty days after that. It is filed with the head of the department or bureau in charge and with the comptroller or the financial officer of the public corporation, not with a county clerk.
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