Massachusetts Condo Special Assessment Calculator (M.G.L. c.183A § 17)

How this calculator works

This calculator computes the per-unit special-assessment math for a Massachusetts condominium under M.G.L. c.183A § 17, including the beneficial-interest allocation, the member-approval-threshold check, the installment-payment schedule, and the financing-alternative monthly amortization.

Inputs:

1. Total project cost requiring the special assessment.
2. Total units in the condominium and the average beneficial-interest percentage per unit.
3. Annual common-expense budget.
4. Master-deed-specified member-approval threshold (default 15% of annual budget if not provided).
5. Number of payment installments (1 = lump sum).
6. Financing alternative: annual interest rate and term in months.

Outputs:

1. The average per-unit lump-sum assessment at the average beneficial interest.
2. The per-1%-beneficial-interest assessment (for varied-interest computation).
3. The project cost as a percentage of annual budget and whether it triggers member-approval requirements.
4. The per-unit per-installment amount under the chosen installment plan.
5. The per-unit monthly payment for the financed alternative, total financing cost, and total interest.
6. An allocation table showing per-unit cost for varied beneficial-interest percentages.

Use the calculator at project-budget development to size the per-unit assessment; use it before noticing the unit-owner meeting to confirm whether member approval is required; use it during owner communication to show the lump-sum vs financed trade-off side by side.

The relevant M.G.L. c.183A statute

Massachusetts condominium assessment authority is governed by M.G.L. c.183A § 17 and related provisions:

§ 6(a) — Common-expense liability is allocated by beneficial interest in the common areas as stated in the master deed. The same allocation applies to special assessments — each unit pays its beneficial-interest percentage of the total assessment.

§ 10(b) — Trustees' powers. The trustees adopt the annual budget, manage the common areas, and have broad authority to operate the condominium subject to the master deed and bylaws. § 10(b) includes the trustees' assessment authority subject to any member-approval limitations in the governing documents.

§ 17 — Trustees' authority to levy regular and special assessments. The trustees may levy special assessments for capital repairs, emergency expenses, and other approved purposes. Many master deeds limit the trustees' unilateral assessment authority by specifying a threshold (commonly 10-25% of annual budget) above which member approval is required.

Key thresholds and Massachusetts-specific gotchas

Allocation is by beneficial interest, not by unit count. A condominium with 100 units does not necessarily assess 1% per unit. The master deed allocates beneficial interest by square footage, by appraised value, or by a formula stated in the master deed. Pull the exact beneficial-interest percentages from the master deed when computing per-unit assessments.

Member-approval threshold varies by master deed. Common thresholds in Massachusetts master deeds are 10%, 15%, and 25% of the annual common-expense budget. Some older master deeds use absolute-dollar thresholds (e.g., $50,000) rather than percentage-of-budget thresholds; absolute-dollar thresholds become outdated as costs inflate. Check the master deed for the specific threshold language; the calculator defaults to 15% as a planning estimate.

Member-approval is typically by beneficial-interest vote. Where member approval is required, the threshold is typically a simple majority of beneficial interest at a meeting where quorum is present, unless the master deed specifies higher (67% or 75%). See the companion quorum-and-supermajority calculator for the voting-math details.

Massachusetts does NOT formally license community-association managers. The lack of manager licensing does not affect the § 17 special-assessment procedure, but boards relying on the manager for project-budget development and unit-owner communication should diligence the manager's experience with capital-project assessments.

Financing rates depend on the association's credit profile. Community-association loans in 2025-2026 typically carry rates of 6-9% with 5-15-year terms. Underfunded reserves, high delinquency rates, or absent audited financials may push rates higher. Obtain term sheets from at least two community-association lenders before deciding on the financing-vs-assessment trade-off.

Unpaid special assessments are enforceable under § 6(c) super-priority. A special assessment that goes unpaid is subject to the same enforcement procedures as unpaid regular assessments — the association may record a § 6(c) verified statement, pursue judicial enforcement under c.254 § 11, or pursue the c.244 power-of-sale procedures. The Drummer Boy rolling-lien doctrine permits successive enforcement actions every six months.

Pending special assessments must be disclosed in the 6(d) certificate. Trustees who are aware of a planned but not-yet-levied special assessment must disclose it in the 6(d) certificate at the time of any conveyance. Failure to disclose may expose the association to claims by the new owner that the assessment is invalid as to them.

Worked example: typical project

Project cost $200,000. 100 units of average 1% beneficial interest. Annual budget $1,000,000. Master deed requires unit-owner approval above 15% of budget. Installments 12. Financing 7% over 60 months.

• Project cost as % of budget: 20% (exceeds 15% threshold).
• Member approval required: YES.
• Average per-unit assessment (lump sum): $2,000.
• Per-unit per-installment: $167 over 12 months.
• Per-unit financed monthly payment: $40 over 60 months at 7%.
• Per-unit total financing cost: $2,376 ($376 interest).
• Verdict: Notice unit-owner meeting; obtain approval; offer installment-vs-financed choice in owner communication.

Worked example: project below threshold

Project cost $100,000. 100 units of average 1% beneficial interest. Annual budget $1,000,000. Master deed requires approval above 15% of budget.

• Project cost as % of budget: 10% (below 15% threshold).
• Member approval required: NO.
• Average per-unit assessment: $1,000.
• Verdict: Trustees may levy without unit-owner vote under § 17.

Worked example: lump-sum vs financed

Project cost $500,000. 100 units of average 1% beneficial interest. Annual budget $1,000,000. Financing 7% over 120 months.

• Average per-unit assessment (lump sum): $5,000.
• Per-unit financed monthly payment: $58 over 120 months at 7%.
• Per-unit total financing cost: $6,970 ($1,970 interest).
• Trade-off: Lump-sum saves $1,970 per unit in interest but creates immediate cash-flow strain. Financing spreads cost over 10 years at $58/month — a manageable addition to monthly common-area fees but at a 40% premium on the project cost.

Most Massachusetts condominium boards offer both options to unit owners: pay the lump-sum within a defined window or convert to the financed monthly schedule.

Worked example: varied beneficial interests

Project cost $300,000. Condominium has units of varying beneficial interest from 0.5% to 3%. Allocation table:

• 0.5% beneficial interest: $1,500.
• 0.75% beneficial interest: $2,250.
• 1% beneficial interest: $3,000.
• 1.25% beneficial interest: $3,750.
• 1.5% beneficial interest: $4,500.
• 2% beneficial interest: $6,000.
• 2.5% beneficial interest: $7,500.
• 3% beneficial interest: $9,000.

The proportional allocation is the c.183A § 6(a) statutory rule and reflects the unit's fractional interest in the common areas. Units with larger beneficial interest pay more in proportion. The trustees cannot reallocate the assessment burden by unit count or by any non-beneficial-interest formula.

What this calculator does NOT model

The calculator implements the PER-UNIT ASSESSMENT and FINANCING-COMPARISON math. It does NOT:

• Model the specific approval procedure required by the master deed (notice content, voting threshold, ballot form).
• Validate the project cost (contractor bids, contingency factors, engineering review).
• Model the reserve-fund adequacy or the optimal split between reserve drawdown and special assessment.
• Project the post-assessment cash flow or delinquency rate for the association.
• Model the tax treatment of the assessment for the unit owners (assessments are typically non-deductible for personal-residence owners; for rental-property owners, they may be deductible business expenses).
• Compute the actual loan amortization for a specific lender's loan (rate adjustments, prepayment options, refinancing).
• Model the impact of the assessment on unit resale value or marketability.
• Validate compliance with the M.G.L. c.183A § 6(d) 6(d) certificate disclosure requirements for the pending assessment.

For any consequential project (above master-deed threshold, requires financing, or involves capital-replacement of major common-area components), retain Massachusetts counsel with c.183A experience to oversee the procedural compliance and engage a reserve-study consultant to validate the project scope and budget.

Counting conventions

The calculator treats the beneficial-interest input as a decimal: 1% = 0.01, 1.5% = 0.015. The framework auto-divides whole-percent inputs (>1) by 100; below 1 is treated as a decimal directly.

The calculator caps total beneficial interest at 100% (1.0) — a single unit's beneficial interest cannot exceed 100% of the common areas.

The allocation table uses sample beneficial-interest percentages from 0.5% to 3% to show the proportional spread. For a specific condominium's exact allocation, compute each unit's assessment as project cost × unit's beneficial-interest percentage.

The financing comparison uses standard amortized monthly-payment math (principal × monthly rate × (1+r)^n / ((1+r)^n - 1)). Zero interest defaults to straight-line allocation (principal divided by term in months).

The installment schedule divides the per-unit assessment by the number of installments without interest — installment plans are typically interest-free for the unit owner (the association absorbs the time value of the receivable).

Sources

Last reviewed: 2026-05-16 against:

• M.G.L. c.183A § 6(a) (common-expense liability allocated by beneficial interest).
• M.G.L. c.183A § 6(c) (six-month super-priority lien for unpaid assessments).
• M.G.L. c.183A § 6(d) (statutory resale certificate must disclose pending assessments).
• M.G.L. c.183A § 10(b) (trustees' powers including assessment authority).
• M.G.L. c.183A § 17 (trustees' authority to levy regular and special assessments).
• Trustees of the Cambridge Point Condominium Trust v. Cambridge Point, LLC, 478 Mass. 697 (2018) (interpretation of c.183A trust-document provisions).
• Community Associations Institute reserve-study standards (AB Reserve Study Standards and Disclosures).
• American Society of Civil Engineers reserve-study guidance.
• Community-association lender practitioner materials (Mutual of Omaha Community Association Banking, Alliance Association Financial Services, Heritage Bank).
• CAI New England chapter practitioner reference materials (Massachusetts condominium capital-project procedure).