A buyer who closes on a Darien home this fall for close to $3 million gets a property tax bill based on what the town said the house was worth on October 1, 2023. The sale price plays no part in it. Darien's median single-family sale price was $1,925,000 in 2023. Through September 30, 2026, it was $2,950,000, according to Houlihan Lawrence's Smart MLS report. The assessment on any given house has stayed put through all of that. The bill has kept rising anyway, because the mill rate has gone up every year since the revaluation reset it.
For anyone comparing Darien with other Gold Coast towns, this means the tax figure on a listing is a snapshot. Between now and 2028, the mill rate pushes it up a little each year. In 2028, a revaluation divides the whole tax load again, and each home's new share depends on how its value has moved compared with everyone else's.
The tax figure on a listing comes from October 2023
Connecticut requires every town to revalue all its property every five years. Darien's most recent revaluation took effect October 1, 2023. In a newsletter to residents, First Selectman Jon Zagrodzky explained that until the next revaluation in 2028, "your value is essentially 'frozen' at what your property was worth on that date."
The exceptions are physical changes. If an owner builds, demolishes, or changes how a property is used, the Assessor updates the value every year based on permits and inspections. A sale doesn't count as one of those changes. The Assessor's online database says the same thing: the appraisal data is based on the 2023 revaluation, and the values set as of October 1, 2025 are the ones used for the July 2026 tax bill.
Zagrodzky put the calculation in one line:
Tax bill = appraised value × 70% × mill rate
The 70% comes from state law, which has set a single assessment ratio for every Connecticut town since 1974. Because assessments stay fixed between revaluations, the mill rate is the only part of the formula that changes for a home nobody has altered.
The mill rate has climbed back since 2024
The 2023 revaluation raised Darien's net taxable grand list from about $8.93 billion to $11.12 billion. Because the tax base was larger, the town could raise its budget at a lower rate. The mill rate fell from 17.61 to 14.69. Since then it has risen in each budget year:
| Fiscal year | Grand list it's levied on | Mill rate |
|---|---|---|
| FY2024 | October 1, 2022 | 17.61 |
| FY2025 | October 1, 2023, the revaluation | 14.69 |
| FY2026 | October 1, 2024 | 15.48 |
| FY2027 | October 1, 2025 | 16.06 |
The town's March 2026 bond official statement has the first three rates. The Board of Finance set the FY2027 rate of 16.06 mills on April 7, 2026, levied on a net assessment of $11,331,239,310, according to the meeting minutes. The FY2026 rate was a 5.38% increase, as reported in the town's FY2025 annual financial report. FY2027 added about 3.75% more. Taken together, the rate is roughly 9% higher than it was right after the revaluation.
Why the town expects the climb to continue
Rising assessments can absorb budget growth, and Darien's have mostly stopped rising. The net grand list was $11.18 billion on October 1, 2024 and $11.36 billion on October 1, 2025, growth of about 1.6%. If the list barely grows, a larger budget has to come mostly from a higher rate.
The town's own finance volunteers said so publicly a year before the FY2027 rate was set. At the May 12, 2025 Representative Town Meeting, RTM Finance & Budget chair Jack Davis told members:
"Most of you know by now that the mill rate increase for FY26 is over 5%. In our opinion, this is not a one-time anomaly. Future years mill rate increases of 4 to 5% should not be unexpected."
Davis listed his reasons in the RTM minutes. He said grand list growth would continue "but not at the same pace," because the revaluation's boost was already counted and "the three major projects have been or are nearing completion." He also expected smaller surpluses from investment income and tax collections, and roughly 4% annual growth in both the Board of Selectmen and Board of Education operating budgets, with healthcare costs rising in both. His statement also included the town's financial strengths: Darien keeps a AAA rating and meets all liquidity guidance. The rising rate reflects a tax base that has stopped growing quickly, and the town remains on solid financial footing.
Homeowners carry most of the load
How much a higher mill rate costs each household depends on who else pays it. On the 2024 grand list, about 90% of Darien's $10.7 billion in real estate value was residential. About 8% was commercial, a figure that includes mixed-use projects like Corbin and Heights Crossing. Zagrodzky compared that with Greenwich, where commercial property is about 14% of the net grand list, and wrote that the difference "helps explain why Greenwich can support a lower mill rate than Darien." He added that as Darien's new developments come fully onto the grand list, "they will help move us in this direction."
You can see those developments in the bond statement's list of largest taxpayers as of October 1, 2025. Three mixed-use or apartment owners rank first, third, and fourth, with Eversource second, followed by Wee Burn Country Club and the Country Club of Darien. Even so, the top ten combined account for only 3.90% of the total. The same document expects future growth to come from mixed-use redevelopment downtown and in Noroton Heights. In the residential neighborhoods, it expects teardowns replaced by new single-family homes that "exceed a million dollars in nearly every instance." Those rebuilds count as physical changes, which is why a new house goes onto the grand list at a new value right away while the 1990s Colonial next door keeps its 2023 assessment.
One house, three bills
Here is a hypothetical home that the town appraised at $2,000,000 on October 1, 2023, with no work done since. Its assessment is 70% of that, or $1,400,000. Multiply by each year's mill rate and divide by 1,000:
- FY2025, at 14.69 mills: $20,566
- FY2026, at 15.48 mills: $21,672
- FY2027, at 16.06 mills: $22,484
The bill went up about $1,900 in two years with no change to the house. If the rate rises 4% a year, the pace Davis described, the bill would keep growing by roughly $900 a year until the revaluation.
The purchase price changes how the bill compares with what the buyer paid. If that same house sold this fall for $2.9 million, the FY2027 bill would come to under 0.8% of the price. The same bill is about 1.1% of the 2023 appraised value. The low percentage on the purchase price holds only until the next revaluation.
In 2028, every home's share gets recalculated
The town's revaluation FAQ says the purpose of a revaluation is to redistribute the tax burden, not to raise revenue. Darien's last one shows how that works. When the town announced the 2023 results, average residential assessments rose between 26% and 33% depending on the neighborhood, and the town said entry-level homes had gone from about $700,000 to about $900,000. The town also said commercial property generally appreciated less than residential, and that owners whose values rose more or less than the town or neighborhood average would see different results. The mill rate then fell from 17.61 to 14.69, which offset much of the higher assessments.
In 2028, the comparison that matters for each home is how its value changed relative to the rest of town since October 2023. The town-wide increase matters much less. Recent sales suggest the market has kept moving. In September 2026, Darien single-family homes sold at a median of $2,581,388, at 105.03% of list price, after an average of 20 days on market, according to Houlihan Lawrence's monthly report. Medians reflect which homes happened to sell, so they don't measure how much any single house appreciated. Still, the move from a $1,925,000 median in 2023 to $2,950,000 through September 2026 shows that the 2023 values now trail the market. A home whose value rose faster than the town average since 2023 will likely take on a larger share of the tax load in 2028. A home whose value rose more slowly will likely take on a smaller one.
Questions buyers ask about this
Does buying a house trigger a reassessment in Darien?
No. A sale isn't one of the triggers. Between revaluations, assessments change only for physical changes like building, demolishing, or changing a property's use, and the Assessor tracks those through permits and inspections.
If I renovate after closing, does my assessment change before 2028?
Permitted physical changes can raise a property's assessment in the next annual update. For a specific project, the Darien Assessor's office is the right place to ask how the work would be valued.
When are Darien tax bills due?
For FY2027, the Board of Finance resolution sets the first installment due July 1, 2026 and the second due January 1, 2027. For a fall closing, that January installment is the next bill coming due.
If you're comparing Darien with Rowayton, New Canaan, or Greenwich, it helps to look at a listing's current tax bill alongside its 2023 assessment and how much it could change by 2028. Stephanie Ogrady can go through the assessor record and tax history for any home on your list. Request a complimentary market consultation.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
