Two buyers are shopping the same weekend. One is looking in Derry, one in Londonderry. Both find a house listed around $500,000. Both assume the tax bill will land somewhere close to the same number, because the prices are close and the towns sit twelve minutes apart on Route 102.
They won't. On an assessed value of $500,000, the Derry buyer is looking at roughly $9,495 a year in property tax. The Londonderry buyer is looking at roughly $7,235. That gap, over $2,000 a year, has nothing to do with school quality, town services, or how well either community is run. It comes down to how each town's tax base is built, and buyers who only compare sale prices walk past it every time.
The rate gap is bigger than most buyers expect
New Hampshire towns set a new tax rate every fall, expressed as dollars owed per $1,000 of assessed value. For 2025, the three towns Julie McMaster's clients cross-shop most often landed in very different places:
| Town | 2025 tax rate per $1,000 |
|---|---|
| Windham | $14.15 |
| Londonderry | $14.47 |
| Derry | $18.99 |
Derry's rate rose $0.30 from 2024's $18.69, a 1.6% increase, according to the town's own tax collector's office. Londonderry's rate actually fell, dropping from $16.14 in 2024 to $14.47 in 2025. Windham's sits lowest of the three. On paper, that makes Windham and Londonderry look like the better tax deal. The real story is more layered, and it matters more the closer you get to writing an offer.
Assessed value is not the same number as the price you'll pay
Before comparing rates across town lines, you have to know what each town's assessed values actually represent, because they are not all measured against the same yardstick.
Londonderry just finished a town-wide revaluation for the 2025 tax year, hiring Whitney Consulting Group to reassess every property using more than 500 qualified sales. The town's stated goal was to bring assessments closer to 100% of fair market value, as recommended by the state's Department of Revenue Administration. Going into that revaluation, Londonderry's equalization ratio for 2024 sat at 85.3%, meaning assessed values across town were running about 15% below what homes were actually selling for. When a revaluation catches assessed values up to market value like that, the rate drops mechanically to raise roughly the same levy off a bigger assessed base. Londonderry's own assessing office is direct about this: an increase in town-wide value generally results in a decrease to the tax rate, and a lower rate does not automatically mean a lower bill.
Derry, by contrast, was not in a revaluation year for 2025. Its assessed base grew the ordinary way, through new construction, additions, and remodeling, which added about $55 million to the town's total valuation of roughly $5.66 billion. That's steady growth, but it doesn't produce the kind of one-time correction Londonderry just went through. Which means the rate comparison above is, in part, a comparison of two towns at different points in their assessment cycles, not two towns with a fixed 30% gap in cost of ownership.
The bigger driver: who else is paying into the pot
The deeper reason Derry's residential rate runs higher isn't timing. It's the mix of who owns taxable property in each town.
Derry's own tax office produced a benchmarking comparison against New Hampshire's ten largest communities, and it puts a number on this. Measured as assessed value per resident, a rough proxy for how much taxable property, including commercial and industrial property, sits behind each person in town, Londonderry comes in at $247,451.94 per capita, the highest figure of the ten communities compared. Derry comes in at $163,389.26, below the group's median of $183,928.32 and fourth from the bottom of the list.
That gap matters because commercial and industrial property owners pay into the same municipal and school budgets homeowners do. A town with more taxable business property per resident spreads its levy across a wider base, which lowers the rate homeowners need to cover the rest. Londonderry carries a larger share of taxable commercial and industrial property relative to its population than Derry does, which is exactly what a per capita figure that much higher signals. Homeowners in Londonderry aren't paying a lower rate because the town spends less. They're paying a lower rate because more of the bill is being picked up by someone else's warehouse or office park.
What Derry's 2025 bill is actually made of
For anyone weighing a Derry purchase, it helps to know where that $18.99 is going, because the pressure isn't evenly spread across the bill. Derry's tax rate is built from four components, and each moved differently for 2025: town taxes rose 2.7%, approved by the Town Council under a charter-mandated tax cap that allowed for up to 3.5%; local education tax rose 1.2%, a budget set separately by the School Board and voters each March; the state education tax actually fell 0.9%, despite its name, since it's assessed and collected locally on behalf of Derry schools; and the county tax jumped 5.1%, a levy divided among all Rockingham County communities based on each town's assessed valuation, not something Derry's town government controls directly.
That last piece is worth sitting with. A buyer moving into Derry isn't just funding Derry's budget choices. They're absorbing a countywide cost that shifts based on how Rockingham County's other towns are valued, a variable no Derry official can negotiate away.
Windham's wrinkle: the rate on the sign isn't always the rate on the parcel
Windham's headline rate of $14.15 looks like the cleanest deal of the three, but it comes with an asterisk that only shows up if you ask. The town's 2025 tax rate notice specifies that certain village districts carry an additional precinct tax layered on top of the base rate: Breezy Gale adds $1.04 per $1,000, and Moeckel Pond adds $0.31. A property inside one of those precincts is paying a real rate closer to $15.19 or $14.46, not the $14.15 headline figure that shows up in most rate comparisons.
This is exactly the kind of detail that never surfaces on a listing sheet. It surfaces when you ask the assessor's office, or when your closing attorney pulls the parcel's tax history and a number doesn't match what you expected.
What to actually ask for before comparing two towns
Before treating a rate difference as the whole story, get these four answers for each property you're seriously considering:
- The current per-$1,000 rate for that specific town, confirmed directly from the town's assessing office rather than a real estate portal
- The town's most recent equalization ratio, so you know whether assessed value is running close to market value or meaningfully below it
- Whether the parcel sits inside a village or precinct district with an add-on rate, as is the case in parts of Windham
- Whether the town has a revaluation scheduled in the near term, since Londonderry completes these roughly every two years and a shift is likely to move the rate again before you've owned the home very long
New Hampshire towns reset their rates every fall, so the 2025 figures above are the current, active rates as of this writing. Derry, Londonderry, and Windham will all set new 2026 rates this fall, and none of them are obligated to move in the same direction.
FAQ
Does a higher tax rate mean a town is managed poorly? Not on its own. Derry's higher rate reflects a smaller commercial and industrial tax base per resident and a county tax that rose independent of any local decision, not mismanagement of the town budget.
If Londonderry's rate dropped, does that mean my tax bill will drop too? Not necessarily. Londonderry's own assessing office warns against using the current rate to estimate a bill, since the drop followed a revaluation that raised assessed values across town. A lower rate applied to a higher assessment can land close to what you paid before.
Where do I find a town's current rate myself? Each town publishes it directly. Londonderry's assessing page, Windham's property tax assessments page, and Derry's tax collector's office all post the current rate and, in Windham's case, any precinct add-ons.
The sale price tells you what a house costs to buy. It doesn't tell you what a house costs to keep, and in Southern New Hampshire, that second number can vary by thousands of dollars a year between towns that look nearly identical on a listing sheet. If you're weighing Derry against Londonderry against Windham and want someone to walk through the actual numbers on a specific property, not just the town average, Julie McMaster and the Property Pros team can pull the current rate, the ratio, and the precinct status before you write an offer. Schedule a free consultation and get the full picture before the number on the closing statement surprises you.
