How is Massachusetts property tax calculated?

Multiply the assessed value by the tax rate expressed per $1,000 of value, then divide by 1,000. For example, a $500,000 home at a rate of $12 per $1,000 owes $6,000 a year before any exemptions.

What is a mill rate in Massachusetts?

Massachusetts towns quote the tax rate as dollars per $1,000 of assessed value rather than a percentage. A rate of $15.00 per $1,000 equals 1.5% of value. Rates vary widely, from under $10 in some towns to over $20 in others.

What is the residential exemption?

Some Massachusetts cities, including Boston, Cambridge, and Somerville, offer a residential exemption that subtracts a fixed dollar amount from the assessed value of owner-occupied homes before tax is applied, lowering the bill for primary residences.

Does Proposition 2 1/2 limit my property tax?

Yes. Proposition 2 1/2 caps how much a Massachusetts community's total tax levy can grow each year, generally to 2.5% plus new growth, unless voters approve an override. It limits the levy in aggregate, not necessarily your individual bill.

Is the assessed value the same as market value?

Not exactly. Massachusetts assessors aim for full and fair cash value, but assessments are set on a schedule and can lag the market. Your assessed value may differ from a recent sale price, and you can request an abatement if you believe it is too high.

Massachusetts Property Tax Estimator

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Massachusetts property tax is based on your town’s assessed value and a tax rate quoted per $1,000 of value. This estimator computes the annual bill and applies the residential exemption offered by some cities for owner-occupied homes.

How it works

The core formula divides the rate by 1,000 because Massachusetts quotes rates per $1,000 of assessed value:

annualTax = (assessedValue − exemption) × (ratePer1000 / 1000)

The residential exemption, where available, subtracts a fixed dollar amount of assessed value for owner-occupied primary residences before the rate is applied. Boston, Cambridge, Somerville, and several other cities offer it; most suburban towns do not.

The effective rate expresses the tax as a percentage of full assessed value:

effectiveRate = annualTax / assessedValue × 100

Example

A $600,000 owner-occupied home in a city with a $10.50 per $1,000 residential rate and a $250,000 residential exemption: taxable value is $350,000, and the tax is 350,000 × (10.50/1000) = $3,675 a year, an effective rate of about 0.61% of the full assessed value.

Notes

Massachusetts rates are set annually and split between residential and commercial classes in many cities, so use your residential rate. The residential exemption only applies to owner-occupied primary homes and is not offered in every community. Proposition 2 1/2 limits total levy growth, not your specific bill. Confirm rates and exemptions with your local assessor.