A Westchester contract signing looks calm from the outside. Both attorneys are on the phone, the deposit is wired, the buyer's lender has cleared conditions. Then somebody pulls the municipal search, or the well test comes back with elevated arsenic, or the title company flags a 1994 oil tank removal permit that was never closed out at Town Hall. Suddenly a June closing is a September closing.
The friction that decides whether a Westchester sale finishes on schedule almost never shows up on the listing sheet. It shows up in a handful of local procedural clocks that start the day the contract is signed, and in a state tax cliff that now lands almost exactly where the county's median single-family price sits.
The $1M line is no longer a luxury problem
The median sale price for single-family homes in Westchester was $1,025,500 in February 2026, up 19.8% from a year earlier, with only 1.3 months of single-family inventory in the county. The HGAR release ran through Westfair in mid-March. Translate that number into transfer tax and something changes about how you write an offer.
New York's additional tax (mansion tax) of 1% of the sale price applies to residences where consideration is $1 million or more, and it is paid by the buyer at closing. Outside the five boroughs, that state 1% is the whole story. The tax applies to the entire price, not just the amount above the threshold.
| Sale price | Buyer's mansion tax |
|---|---|
| $995,000 | $0 |
| $1,000,000 | $10,000 |
| $1,050,000 | $10,500 |
| $1,100,000 | $11,000 |
Look at row one and row two. Five thousand dollars of price becomes a ten-thousand-dollar swing in cash-to-close, because the mansion tax cannot be financed into a mortgage — it must be paid in cash at closing. When the county median sits at $1.025M with 1.3 months of supply, a large share of Westchester single-family deals are being written within a rounding error of that cliff. Sellers who understand the geometry price at $999,000 and take the extra bidder. Buyers who understand it push a $1,010,000 asking price toward the same number and pocket the swing.
That is the negotiating leverage most out-of-market brokers do not see when they look at the median.
The 10-day clock a private well starts
Roughly one in every set of Westchester listings north of the Kensico Reservoir sits on a private well. The moment that contract is signed, the seller is on a clock created by the Westchester County Code.
Under Chapter 707, upon the signing of a contract of sale for any property within Westchester County served by a private well, the seller shall cause a water test to be conducted, arrange and pay for the cost of this testing, and within ten days of the execution of the contract, provide the purchaser with confirmation that the test has been ordered. Then within five days of receipt of the water test results from a certified laboratory, the seller shall deliver the water testing report to the purchaser, and both sides certify in writing that they received and reviewed the results.
Three details that catch people:
- The buyer and seller cannot waive it. A copy of the test results must be sent by the laboratory to the Westchester County Department of Health, which is the reason the parties do not get to skip the step even by agreement.
- The sample must come from a specific list. Only laboratories certified by the New York State Department of Health and registered with the Westchester County DOH can collect and submit the sample, and one lab must coordinate all results electronically to the county.
- The test panel is not short. All wells must be tested for total coliform bacteria; nitrate, arsenic, lead, all primary organic contaminants including in Part 5 of the New York State Sanitary code, vinyl chloride; and methyl-tertiary-butyl-ether (MTBE); and the following secondary contaminants: pH, iron, manganese, sodium and chloride. If total coliform comes back positive, a follow-up E. coli or fecal coliform test is required, which adds days.
A primary contaminant failure does not automatically kill the deal, but it starts a remediation and treatment negotiation that sits on top of an already tight closing calendar. Sellers who order the test the day the contract is signed protect their closing date. Sellers who wait a week because "the buyer's home inspector will probably do it anyway" find themselves running the treatment install in the last two weeks before closing.
The law has been in effect since Nov. 19, 2007. It is not new. It is still the single most common reason a northern Westchester closing gets pushed.
The oil tank problem is a records problem
There is a version of this story on every Westchester block built before 1980. A house converted from oil to gas heat in the 1990s. The homeowner paid a contractor, the tank came out, life moved on. Twenty-five years later, the buyer's attorney orders a municipal records search and finds an oil tank removal permit that was pulled but never closed out with the town's building department.
That open permit is a title-marketability problem before it is an environmental one. As the Westchester real estate attorney Betensky Law describes it, in the State of New York, environmental issues often arise in the context of residential real estate transactions. A home inspection report may indicate the presence of mold or asbestos. A municipal search in a title report may indicate that an oil tank removal permit remains open.
The New York Property Condition Disclosure Act requires the seller of residential real property to cause this disclosure statement or a copy thereof to be delivered to a buyer or buyer's agent prior to the signing by the buyer of a binding contract of sale, and the form itself asks directly, at question 18, whether petroleum products have ever spilled, leaked, or been released on the property. Question 19 asks whether the property has been tested for those substances. A seller who checks "Unknown" on a house that visibly converted from oil is not a seller a Westchester buyer's attorney will let their client close on without additional comfort.
Two things move faster when you deal with this pre-listing rather than mid-contract. The town closes out the permit. And the buyer's homeowner's insurance carrier stops treating the property as uninsurable, which is where deals actually die.
Why "everyone opts out" of the disclosure form
New York is one of the states where sellers routinely refuse to complete the state disclosure form and instead deliver a $500 credit to the buyer at closing. The PCDA requires home sellers to make certain disclosures about material defects in the property or pay a credit of $500 to the home buyer at closing. Many if not most home sellers in New York actually opt not to complete the statement, and instead pay the credit.
Here is the misconception that ends up in litigation: the $500 is not a liability shield. Many New York sellers' attorneys interpret this relatively low penalty as an opportunity for their clients to opt out of the PCDA by paying the $500 in lieu of providing the form, and see this as avoiding the risk of potential liability for misstatements on the form. However, paying the $500 statutory remedy does not protect you from liability under the case law exceptions to caveat emptor.
For a Westchester seller, the practical read is this. Taking the credit is defensible when the house is in good, well-documented condition and the seller genuinely does not want to warrant a form they only half-understand. It is a bad idea when there is a known issue the seller is hoping the buyer will not ask about, because "I paid the $500" is not the sentence that gets you out of a fraudulent-concealment claim two years later.
Buyers reading this: when the seller opts out of the form, that is your cue to tighten the inspection contingency and the rider, not to walk away.
A pre-listing checklist that saves a Westchester closing
Before you accept an offer, get these on paper:
- A recent municipal records search from the town, not just the county. Open permits live at the town.
- If the house is on a well, pre-select the certified lab. When the contract is signed, one email starts the Chapter 707 clock instead of three days of scrambling.
- If the property has ever been on oil heat, a locate scan of the yard and a copy of the removal invoice from the contractor who did the work.
- A radon test result less than two years old, so the buyer's radon contingency does not compress the closing window.
- A candid conversation with your attorney about whether to complete the state disclosure form or accept the $500 credit at closing.
- If the likely sale price is between $995,000 and $1,050,000, a pricing conversation that acknowledges the mansion tax cliff exists on the buyer's side of the ledger.
Each of these is a two-hour task done in April. Each of them becomes a two-week problem in June.
Frequently asked questions
Does the Westchester well water test law apply to a rental? Yes. The law reaches leased properties served by private wells, not only sales. Owners of well-served rentals should confirm the current testing cycle with the county DOH before advertising a vacancy.
If our well test fails a primary contaminant, do we have to install treatment before we can close? Not automatically. Section 3.0 of the Westchester County Health Department Rules & Regulations addresses required remediation, and the parties can negotiate whether treatment is installed as a condition of closing, whether a credit covers the buyer's cost, or whether the deal is restructured. What you cannot do is close without the paperwork exchange the law requires.
Is the $1M mansion tax the same in Westchester as in Manhattan? No. The New York State 1% applies statewide at $1M and up. The additional progressive tiers that push NYC rates to 3.9% at the very top do not apply outside the five boroughs. For most Westchester single-family deals, the buyer's exposure is a flat 1% of the sale price at $1M or above.
We are converting an oil house to gas this year. Does that affect a future sale? It changes what your future disclosure has to acknowledge. Keep every invoice, the town's closed permit, and any soil-testing report from the removal contractor. Buyers' attorneys ask for that packet by name.
If you are getting close to a Westchester listing decision, or you are already under contract and one of these clocks has started ticking, the difference between a June closing and a September closing is usually a phone call made in the right week. Reach out to Vision Alliance Realty and we will walk through your specific property, your timeline, and your paperwork before the friction finds you. Start Your VIP Home Search when you are ready.
