Boston property tax relief calculator: 2026 residential exemption & condo timing

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Boston’s Assessing Department has a Property Tax Relief Calculator designed to help residents estimate how Mayor Wu and the City Council’s 2026 property tax relief proposal could translate into FY26 tax-bill impacts. But Boston stresses this is an estimate, not a guarantee—especially because the City says it still must mail bills under existing state law. Under that approach, Boston projects an annual tax bill increase of 13% for the average single-family home receiving a residential exemption.

What the calculator is meant to estimate (and what it can’t) i

Boston’s calculator page explains that the “latest version” of the relief legislation (filed with the Legislature in February 2025) “has not been assigned to a committee by the State Senate.” As a result, Boston says the City must proceed with mailing out tax bills under existing state law—leading to the projected 13% annual increase for the average eligible single-family home, with some households seeing higher increases based on their individual property valuations.

The calculator itself is structured to help residents model that kind of expected impact for FY26—not to predict the exact amount of your final bill.

How to use Boston’s Property Tax Relief Calculator i

Boston says you can use the tool in two ways:

• Search your address through the calculator, or
• Enter the estimated FY26 value for the property.

If you don’t have a confident FY26 value number, the City’s own instructions point you to entering an estimate yourself. The key is to remember: the actual assessment and final FY26 tax outcome depend on how Boston’s assessing records apply to your property for the fiscal year.

Why many bills may still rise even with “relief” i

Boston’s central point is that, absent the additional flexibility it is seeking through the relief legislation, the City still expects tax bills to be mailed under existing state requirements. Under that baseline, Boston projects the 13% annual increase for the average eligible single-family home with a residential exemption. Individual results can differ up or down depending on valuation and eligibility details.

FY26 timing: when residents usually see changes (and when they don’t) i

To connect the calculator estimate to the bills residents actually receive, Boston’s FY2026 Assessing Calendar emphasizes a core Massachusetts rule:

• Property is assessed at full market value as of January 1 preceding the start of the fiscal year.
• Ownership, condition, and value on January 1 determine the assessment and who is assessed.
• Changes after January 1 generally won’t be reflected in assessing records until the next January 1.

The same calendar lays out how FY26 bills tend to flow through the year:

• July 1: 1st Quarter preliminary tax bill issued (based on the prior fiscal year’s taxes).
• October 1: 2nd Quarter preliminary tax bill issued.
• Late December: 3rd Quarter actual tax bill issued reflecting the actual value and tax rate for the fiscal year.
• April 1: residential exemption and tax deferral filing deadline, and the 4th Quarter tax bill is issued.

Since FY2026 runs July 1, 2025 to June 30, 2026, the underlying assessment value example in Boston’s calendar points to the January 1, 2025 status for FY26.

Condo conversions: why the January 1 status rule can shift whose bill you see (and when) i

Condo conversions can make tax timing feel counterintuitive. Boston’s guidance on “Condo conversions and tax bills” explains that for a given fiscal year, tax bills “always reflect the status of the property on January 1 prior to the start of the fiscal year.” If a property is sold or its use changes, those updates aren’t immediately reflected in the tax bill.

Boston also notes there may be a time before each unit owner receives an individual bill, and that each unit owner is responsible for a share of the total property tax bill based on their percentage interest in the common area.

Boston provides a timing example for conversions: for the 2027 fiscal year, “most condo conversions recorded before January 1, 2026” will get first-quarter tax bills on July 1, 2026. If there’s a big conversion or an issue recording it, Boston says tax bills may be sent in the third quarter.

Practical takeaway: when conversion paperwork lands around the January 1 assessment-date framework, it can affect when the unit-level bill you care about first reflects that new status—so plan around the fiscal-year calendar, not just the sale/conversion date.

What to do next i

If you’re trying to plan for FY26, use Boston’s calculator as a starting point—then “sanity-check” the output against what you expect your property’s assessed value story to be for the fiscal-year cycle. And if you own a condo or are considering a conversion, treat the January 1 status framework as central to understanding when tax impacts show up for different owners.

Sources

• Mayor Wu’s 2026 Property Tax Relief Calculator (Boston.gov)
• FY2026 Assessing Calendar (Boston.gov PDF)
• Condo conversions and tax bills (Boston.gov)

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