Blackstone & Millville Tax Impact Calculator
Proposed Blackstone‑Millville Regional High School

1Your town and your home

Enter either your assessed value or your current annual tax bill. The other is derived from the tax rate in section 3.

Side by side: the two towns

Same project, same financing, each town's own share and tax base. Year‑1 figures under the structure selected in section 2.

2How the bond is repaid

This is the single biggest driver of the year‑one number. Massachusetts municipalities most often issue bonds with level principal (equal principal each year, so payments start high and decline). Level debt service (equal total payment every year, like a mortgage) is also used and produces a flatter but higher‑interest schedule. The district has not announced which it will use.

3All assumptions (edit any of them)

Defaults are shown with their source. Nothing is hidden: if a number is an estimate rather than a published figure, it says so.

Project cost

Financing

Tax base — Millville

These three fields belong to the town selected in section 1. Switch towns and they swap; edits are kept per town.

4Your added tax, year by year

Both repayment structures shown for the same principal, rate and term. Hover or tap for values.

5Full repayment schedule

Every year of the bond for the structure selected in section 2. "Rate add" assumes the town's total valuation stays constant (see caveats).

6How the math works

Every result on this page comes from these formulas and nothing else. Live values from your current inputs are shown in each step.

Step 1 — The town's principal

Principal = Towns' share × (1 + overrun%) × Town share% Millville share% = the input in section 3; Blackstone share% = 100% − Millville share%

Step 2 — Annual debt service

Level debt service: Payment = Principal × r / (1 − (1 + r)⁻ⁿ) where r = rate, n = term in years Level principal: Principal paid each year = Principal / n Interest in year k = r × (Principal − (k−1) × Principal / n) Payment in year k = Principal / n + Interest in year k

Step 3 — Convert to a tax rate

Rate add (per $1,000) = Annual payment ÷ Total taxable valuation × 1,000 A debt exclusion is a fixed dollar amount raised outside the Proposition 2½ levy limit and spread across every taxable property in proportion to assessed value. This is the mechanism Massachusetts uses for school building debt.

Step 4 — Your bill

Your added tax = Your assessed value ÷ 1,000 × Rate add Percent increase = Your added tax ÷ (Your assessed value ÷ 1,000 × Current tax rate) If you entered a tax bill instead, assessed value = bill ÷ current rate × 1,000.

Step 5 — Today's dollars (optional)

Real cost in year k = Nominal cost ÷ (1 + inflation)^k−1 Only used in the chart/table "today's $" view when inflation is set above 0%.

7Sources

1. Town of Millville — 2025 Annual Town Report (PDF): FY2025 total assessed valuation $456,176,188 across 1,319 parcels (93.35% residential); tax rate $13.19; levy $6,016,964; average single‑family value $422,300.
2. Town of Millville Assessors — Tax Rates: FY2026 real estate rate $12.21; FY2025 $13.19; FY2024 $13.22.
3. Town of Millville Assessors — FY2026 revaluation notice: single‑family values up ~11% for FY2026; link to proposed FY2026 values by street.
4. Town of Blackstone — FY2026 Tax Classification Hearing (Dec 9, 2025, PDF): aggregate valuation $1,675,511,471 (residential $1,366,706,735, 81.6%); FY2026 levy $24,697,039; average single‑family value $464,214 at $14.74 → $6,842.51; FY2025 average $424,433 at $15.10 → $6,408.94; FY2025 levy $23,760,487.
5. Town of Blackstone — Tax Rate & Due Dates: FY2026 $14.74; FY2025 $15.10.
6. FY2026 average single‑family tax bills by town (DLS data as republished by Lamacchia Realty): Millville $5,762 at $12.21 → implied average value $471,900; Blackstone $6,843 at $14.74 (matches the Town's own figure above).
7. BMRSD Three‑Year Financial Plan (2017, PDF): illustrates capital‑cost apportionment "based on enrollment" at Blackstone ~71% / Millville ~29%.
8. LocalLens — School Committee moves forward with $197M building project.
9. Small Town Post — BMR school building project design vote: preferred option ~$195.9M, construction ~$150.7M, MSBA reimbursement up to 58% of eligible costs, contingencies could push total to ~$210M.
10. MSBA — Board votes BMR High into Schematic Design (Feb 25, 2026).
11. Blackstone‑Millville Regional Agreement — governs how capital costs are split between the towns.

Caveats — read these before quoting a number

• The town split is the softest input. The regional agreement apportions capital debt by enrollment, recomputed every year for the life of the bond. A few points of enrollment drift moves every bill in both towns proportionally — in opposite directions.
• Why Millville's rate impact is higher than Blackstone's. Millville's tax base is roughly $0.5B vs Blackstone's $1.7B (about 23% of the combined base), but the enrollment split assigns it ~27% of the debt. Same house value, slightly bigger bill. Blackstone also carries ~$235M of personal property (utility and business equipment), which absorbs part of its share.
• The towns' share may change. $115.8M is the current published figure. Overruns above MSBA caps are entirely local, which is why the overrun input exists.
• Valuation is held constant. The calculator spreads a fixed payment over today's tax base. As the base grows (new construction, revaluation), the rate add falls — but so does your home's proportion only if it grows slower than the town. Your dollar cost is roughly stable in nominal terms; your percentage increase shrinks as the rest of your bill grows ~2.5%+ per year.
• Timing. Debt‑exclusion payments typically begin when short‑term notes or bonds are first issued — during construction — not when the building opens.
• Financing costs are excluded from the headline figure. The published $115.8M is principal only. Interest roughly adds 55–75% on top over 30 years at 4–5%.
• This models the debt exclusion only. It does not include any change to the district's operating budget, which goes through the regular levy.