The Common Mill
A mill rate is dollars of tax per $1,000 of assessed value. Every town sets its own assessed value, so the published rates are not in the same unit and cannot be put side by side. The City of Rye publishes a school rate of 767.368201. Larchmont publishes 12.451323. That comparison is meaningless as it stands.
The Common Mill is the same figure measured against what a house is worth: estimated annual tax per $1,000 of full market value. One unit, every town.
The 2026 Common Mill
| Town | Common Mill | $1,000,000 house | $2,000,000 house | $3,000,000 house | Houses measured |
|---|---|---|---|---|---|
| Rye | 14.24 | $14,237 | $28,473 | $42,710 | 3,718 |
| Scarsdale | 18.01 | $18,013 | $36,026 | $54,039 | 5,069 |
| Larchmont | 21.12 | $21,123 | $42,245 | $63,368 | 1,459 |
| Mamaroneck | 21.19 | $21,193 | $42,386 | $63,579 | 3,004 |
Mamaroneck costs 49% more per dollar of house than Rye. On a $2,000,000 house that is a difference of about $13,912 a year.
Why the published rates mislead
Each town applies its rates to a different fraction of market value. That fraction is the third column here, and it is what makes the first column unreadable across a row.
| Town | Published rates, summed | Assessed as % of market | Common Mill |
|---|---|---|---|
| Rye | 1,206.50 | 1.18% | 14.24 |
| Scarsdale | 26.92 | 66.91% | 18.01 |
| Larchmont | 21.12 | 100.00% | 21.12 |
| Mamaroneck | 21.19 | 100.00% | 21.19 |
Multiply the second column by the third and you get the fourth. That is the whole calculation.
What this is and is not
- An estimate, not a bill. It applies published mill rates to the roll. Special districts, unusual parcels and mid-year changes are not in it.
- Before exemptions. The Rye and Mamaroneck rolls carry no exemption codes at all, so nothing is deducted for STAR. A real bill is usually lower. Scarsdale applies STAR where the roll records it, which is 380 parcels.
- Market value comes from the roll, not from sale prices. Each town derives it from assessed value using one equalization ratio, so the figure is the town's own view of what its houses are worth.
- It measures the town, not your house. Two houses in the same town have the same Common Mill. What differs is what they are assessed at.
Work out a specific price · How Westchester property tax works
FAQ
What is the Common Mill?
Estimated annual property tax per $1,000 of a home's full market value. Published mill rates are per $1,000 of assessed value, and every town assesses on a different basis, so they cannot be compared directly.
Why can't I just compare published mill rates?
Because they are applied to different bases. The City of Rye assesses at about 1.18% of market value and Larchmont at 100%, so Rye's rates are roughly eighty times larger for the same tax.
Which town has the lowest property tax?
On the 2026 rolls, Rye has the lowest Common Mill at 14.24 and Mamaroneck the highest at 21.19.
Is this my actual tax bill?
No. It is an estimate from published mill rates, before exemptions, and it excludes special districts. Confirm with the assessor and your bill.
Unofficial. Confirm figures on each edition’s official roll or PROS before decisions.