Listings show the seller's reduced bill. When you buy, all of that disappears. This calculator pulls the assessor's data on any LI property and shows what your bill becomes once exemptions roll off — so you can budget honestly before making an offer.
We pull live data from the NY State assessment roll — the same data the County uses to bill the property.
A defensible rule of thumb for new LI homeowners:
The combined effect: STAR credit + grievance + any veteran/senior exemptions can bring your bill to within 5-10% of the seller's within 18 months.
Plug the address into our calculator. If the property has STAR, Senior, Veteran, or other exemptions, those will drop off at closing. Your real bill is likely 10-30% higher in the first year before you register your own STAR.
Yes. Mortgage lenders calculate your debt-to-income (DTI) ratio using the full property tax bill including exemptions you don't yet qualify for. Some lenders will use the seller's bill if it's in escrow. If you're borderline on DTI, ask your loan officer to use the post-exemption-loss number.
Rare but happens. More common: ask for a credit at closing covering the difference between the seller's bill and your projected first-year bill. Your buyer's agent should run the numbers.
New construction is assessed once the certificate of occupancy is issued. Until then, your bill is based on the land assessment only. Once assessed, the bill jumps significantly. Plan for the first full year to land at roughly 1.5-2.5% of purchase price for typical LI homes.
Enter any Long Island address to see the median bill for the district, your projected bill if you bought today, and how exemptions roll off after a sale.
Open the calculator →Grievance deadlines, STAR limit updates, new exemption laws. One short email, only when something actionable happens. Unsubscribe in one click.
Subscribe →Last verified: 2026-05-11. Tax rules change; we re-verify each page quarterly.
Estimates and educational content only — not legal, tax, or financial advice. Verify with your county or town receiver, an attorney, or a CPA before making financial decisions.