The residential exemption: property-tax math for year-rounders

Two houses on the same lane, assessed at the same value, can carry very different tax bills on Nantucket. The difference is usually not a quirk of assessment. It is the residential exemption — a deduction that Massachusetts law allows and the Select Board adopts each year, available only to owners for whom Nantucket is their primary, legal home.

Most year-round buyers have never heard of it, because most mainland towns never adopt it. Nantucket has, every year — and for a domiciled owner it belongs in the ownership math from day one.

Each year the Select Board votes whether to adopt the exemption and at what percentage — state law allows up to 35 percent, and Nantucket has adopted 25 percent every year since fiscal 2018. The percentage is not taken off your own home's value. It is calculated against the town-wide average residential value — every Class 1 residential parcel, vacant land included, averaged together. That average is multiplied by the exemption percentage, and the resulting dollar amount is deducted from the assessed value of every qualifying home before the tax rate is applied.

In fiscal 2026 that deduction is $899,277 of assessed value per qualifying home. At this year's residential rate of $3.12 per $1,000, it is worth about $2,806 a year — every year you qualify. The dollar amount is recalculated annually as values move: it was $827,969 in fiscal 2025 and $799,150 in fiscal 2024, so treat any printed figure, this page's included, as good for its fiscal year and refreshed each December. The mechanism does not change; the numbers do.

The exemption is not free money; it is a shift. The residential class raises the same total levy either way — the exemption moves a share of it from domiciled year-rounders onto owners for whom Nantucket is not their legal home. On most of the mainland that trade barely moves the needle. On an island where seasonal and investment owners hold the majority of the residential value, the arithmetic is unusually favorable to the year-rounder: many shoulders pick up the shifted weight, and each carries only a sliver.

That is also why the exemption pairs with an already-low rate. Nantucket's tax rate stays low for the same structural reason — an enormous taxable base relative to the cost of running the town. The exemption sits on top of that as the year-rounder's second advantage.

The standard is domicile, not occupancy: Nantucket must be your primary, legal residence as of January 1 of the year before the fiscal year in question — the address on both your federal and Massachusetts income-tax returns. A summer house you use heavily does not qualify. A winter rental you live in does not qualify either, because the exemption belongs to owners.

Qualifying is one thing; receiving it is another. The assessor's office does not enroll anyone automatically — it is the owner's job to claim it.

Applications go to the Board of Assessors within three months of the date the tax bills are mailed. You will need the first pages of your federal and Massachusetts returns for the qualifying year — the office allows you to redact Social Security numbers and income figures, but the property address must be visible. Owners who use a P.O. Box should expect to provide additional documentation.

Once granted, the exemption generally carries forward without annual reapplication. It ends when the facts that earned it end — you sell, ownership changes, or the house stops being your primary residence.

For a year-round buyer, the exemption is a permanent, recurring reduction most first-time island buyers do not know to expect — put it in the ownership model from the first offer. For a seasonal buyer, its absence is worth understanding too: the tax figure on a listing may reflect the seller's exemption, and your bill as a non-domiciled owner will be modestly higher than the one the listing implies.

Either way, the assessed value driving all of this is a taxation number, not a market opinion — we wrote separately about why an assessment is never a stand-in for what a house is worth. This page describes the town's published rules in plain language; it is not tax advice. For how the exemption interacts with your returns, trusts, or ownership structure, bring it to your accountant — and for what a specific house would actually cost you to hold, ask us.

Run the ownership math before you offer