The annual property tax on a Londonderry listing sheet is the seller's assessed value multiplied by the town rate. A buyer keeps that same assessed value until the town revalues, and the rate changes each year as the budget does. At a revaluation, the bill moves based on how that one property's value changed compared with every other property in town. The sale price doesn't drive it, and neither does the headline rate. Comparing Londonderry, Derry, and Windham by tax rate alone mostly compares where each town is in its revaluation cycle.
The 2025 numbers show this more clearly than any recent year.
The Rate Dropped While the Levy Rose
Londonderry's assessing department finished a full statistical revaluation in 2025. Under the Town Council's biennial policy, the previous one was in tax year 2023. Here is what happened to the town's tax math, according to the New Hampshire Department of Revenue Administration's 2024 and 2025 tax rate calculation data:
| Londonderry | Tax year 2024 | Tax year 2025 |
|---|---|---|
| Total tax rate per $1,000 | $16.14 | $14.47 |
| Total tax effort | $102,325,573 | $105,525,946 |
| Total property tax commitment | $101,320,823 | $104,455,196 |
| Valuation used, including utilities | $6,390,693,763 | $7,345,963,764 |
From 2024 to 2025 the rate fell about 10 percent while the amount raised grew about 3 percent. Assessed values went up faster than spending did. Since the rate is the levy divided by the total valuation, the rate came down.
Each component fell in the same way. The municipal portion dropped from $3.77 to $3.53 even though its dollar amount rose from $24.1 million to $25.9 million. Local education went from $10.40 to $9.28 while its dollars rose from $66.4 million to $68.2 million. All of the rate cut came from the denominator.
Who Carried the Extra 3 Percent
A rate drop on a growing levy means some owners pay more and some pay less. Which owners depends on how each property's value changed compared with the town as a whole. The assessor's September 2025 revaluation report gives preliminary category figures. Single-family property rose 15.90 percent, condominiums rose 19.80 percent, and commercial property, which includes commercial apartments, rose 7.92 percent.
You can estimate the bill effect by applying the 10 percent rate drop to each category's average change:
- Single-family, average change: a bill up roughly 4 percent
- Condominium, average change: a bill up roughly 7 percent
- Commercial, average change: a bill down roughly 3 percent
This is a rough calculation. The category figures were preliminary and left out utility property, which was still being valued at the time. Individual homes within each category moved by different amounts. The report says so itself, warning that a higher assessment does not necessarily mean a higher tax bill.
The same figures show commercial property's share of preliminary taxable value falling from about 25.0 percent to about 23.6 percent. The assessor called it a "slight reduction." Many buyers assume the industrial and logistics growth around Manchester-Boston Regional Airport lowers homeowners' share of the levy. In 2025 the residential share went up slightly. At a January 2025 Town Council discussion about extending the commercial and industrial tax incentive program, Councilor Farrell said the realistic goal was tax stabilization and that no one had promised taxes would decrease. In the same discussion, Farrell said commercial valuations statewide were not growing as fast as residential ones.
Why Windham Looked So Much More Expensive in 2024
The listing-sheet problem matters most for buyers comparing towns. Here are the three towns on both measures, from DRA's 2024 and 2025 full-value tax rate comparisons and its municipal rate schedules:
| Town | 2024 nominal rate | 2024 equalization ratio | 2024 full-value rate | 2025 nominal rate | 2025 equalization ratio | 2025 full-value rate |
|---|---|---|---|---|---|---|
| Londonderry | $16.14 | 86.3% | $13.72 | $14.47 | 95.2% | $13.52 |
| Windham | $22.64 | 59.4% | $13.37 | $14.15 | 96.4% | $13.55 |
| Derry | $18.69 | 92.4% | $16.75 | $18.99 | 90.8% | $16.73 |
The equalization ratio is DRA's estimate of how close a town's assessments are to market value. The full-value rate divides the property taxes to be raised by the town's total equalized valuation. That puts every town on a market-value basis, so it holds up as a town-to-town comparison when assessment ratios differ.
In 2024, Windham's nominal rate was $6.50 above Londonderry's. On a full-value basis Windham was 35 cents lower. Windham's assessments averaged about 59 percent of market value, so its rate had to be higher to raise the same money. Windham's 2025 reassessment raised overall assessed value by 67.3 percent. In its November 20, 2025 tax rate release, the town said the reassessment itself did not increase the total taxes raised. Windham's commitment still rose, from $71,744,793 to $75,007,439, and its rate fell to $14.15.
Now that both towns are near full assessment, their nominal and full-value rates nearly match, and Londonderry and Windham differ by 3 cents per $1,000 of market value. Derry's full-value rate is about $3.20 higher than either. That gap shows up on both measures and doesn't depend on the revaluation calendar. Derry's commitment rose from $104,098,329 to $106,799,960 over the same period.
What a Seller's Tax Bill Tells a Buyer
New Hampshire doesn't reset a home's assessment when it sells. The buyer takes over the seller's assessed value and keeps it until the next town-wide update. Windham's 2025 revaluation guide explains that after an update, each bill depends on how that property's value changed relative to the town's total valuation. So the listing-sheet figure is a reliable number for a stretch of time, and the length of that stretch depends on the town's cycle.
Three questions show how much weight the figure can bear:
- How close is the town's equalization ratio to 100 percent? Londonderry was at 95.2 percent and Windham at 96.4 percent for 2025. At those levels, current assessments are close to market and the inherited bill should be a reasonable guide. At Windham's 2024 ratio of 59.4 percent, it would not have been.
- When is the next revaluation? Londonderry's council set a biennial cycle, and the last update was in 2025, which puts the next one in 2027. Windham says it revalues every five years. Derry's assessing site has a page titled "2026 Revaluation," but its details could not be confirmed. If Derry does revalue for 2026, its nominal rate could move for reasons that have nothing to do with its budget.
- Is the home's category gaining value faster than the town overall? In Londonderry's 2025 update, condominiums outpaced single-family homes, and both outpaced commercial property. A category that keeps outpacing the town at the next revaluation takes on a larger share of the levy.
Where 2026 Stands in October
As of mid-October 2026, DRA's municipal reports list 2025 rates and no 2026 municipal rates, so 2025 is the most recent finalized year for all three towns.
Londonderry's spending decisions for the year are known. Patch reported that the $56,592,573 FY2027 operating budget passed 2,529 to 1,856 in unofficial March 10 results. The $3.38 million Morrison Meeting House bond failed 894 to 3,515. The town warrant estimated the operating budget would require $28,070,432 in property taxes, with a projected rate impact of $3.728. In January, a town estimate updated January 20, 2026 projected a FY2027 municipal component of $4.235, using an anticipated 2026 assessed valuation of $7,529,589,833. These are projections for one of four rate components. The final figure depends on the valuation DRA uses when it sets the rate.
2026 is not a scheduled revaluation year in Londonderry, so the denominator won't jump the way it did in 2025. Any rate change this fall will reflect spending and ordinary growth in the tax base.
Frequently Asked Questions
Does a lower tax rate after a revaluation mean lower taxes? Not necessarily. Londonderry's rate fell from $16.14 to $14.47 between 2024 and 2025, and the total amount the town raised increased. An individual bill depends on how that property's assessment changed relative to the whole town.
Which number compares New Hampshire towns most fairly? The DRA full-value tax rate, because it adjusts for how close each town's assessments are to market value. For 2025 it was $13.52 in Londonderry, $13.55 in Windham, and $16.73 in Derry.
Will my assessment change when I buy a home in Londonderry? A sale does not reset the assessment. The buyer keeps the seller's assessed value until the next town-wide update, which on Londonderry's biennial schedule would come in 2027.
If you're weighing a home in Londonderry, Derry, or Windham and want the tax figure on a specific property checked against that town's equalization ratio and revaluation calendar, Rebecca Curran Realty can go through the numbers with you before you make an offer or set a list price. Get Your Instant Home Valuation to see where your current assessment sits relative to today's market.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
