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Mass Save covers 75% of insulation costs for every Massachusetts customer. Income-eligible households pay nothing. Attic, wall, basement, and air sealing -- all with instant rebates applied at installation.
Last updated February 2026 | Federal 25C tax credit EXPIRED Dec 31, 2025
All Mass Save customers qualify for the 75% rebate. Income-eligible households receive 100% coverage at no cost.
Most homeowners pay just 25% of insulation cost
Fully covered — $0 out of pocket for qualifying households
Five key insulation and air sealing measures, with costs before and after Mass Save rebates.
| Measure | Typical Cost | After 75% Rebate Standard | Income-Eligible 100% Covered | R-Value | Comfort Impact |
|---|---|---|---|---|---|
Attic Insulation Blown-in fiberglass or cellulose over existing insulation. Most impactful single measure for comfort. | $1,500-$4,000 | $375-$1,000 | FREE | R-49 to R-60 | High |
Wall Insulation (Dense-Pack) Dense-pack cellulose through small drill holes in exterior siding. Minimally invasive — holes patched after. | $2,000-$6,000 | $500-$1,500 | FREE | R-13 to R-15 | High |
Basement/Crawlspace Insulation Rim joist spray foam + wall insulation. Dramatically reduces cold floors and drafts. | $1,500-$4,000 | $375-$1,000 | FREE | R-15 to R-25 | High |
Air Sealing Seal air leaks found during blower door test — attic bypasses, electrical penetrations, plumbing stacks. | $800-$2,500 | $200-$625 | FREE | N/A (CFM50 reduction) | High |
Duct Sealing & Insulation Seal leaky ductwork joints and insulate exposed ducts. Can improve HVAC efficiency 20-30%. | $500-$1,500 | $125-$375 | FREE | R-8 duct insulation | Medium |
Costs vary by home size, existing insulation levels, and accessibility. Your assessment report provides exact costs and rebate amounts for your home.
Maximum savings when you do everything at once
Typical Total Cost
$6,300-$18,000
After 75% Rebate
$1,575-$4,500
Annual Energy Savings
$400-$1200
Payback Period
1-3 years
Dramatically reduces drafts, cold spots, and ice dams. Evens out temperatures between floors.
HEAT Loan option: Finance your 25% share with a 0% interest HEAT Loan up to $25,000. A $4,000 remaining cost is just $48-$111/month depending on your income tier.
One contractor, one project: NuWatt coordinates insulation, heat pumps, and water heaters as a single project — one contractor, one HEAT Loan application, one timeline. Bundling typically saves 2-4 weeks compared to hiring separate contractors.
The process is straightforward. Mass Save handles most of the complexity, and your rebate is applied instantly at installation.
Call 866-527-7283 or schedule online at masssave.com. The assessment takes 2-4 hours and is completely free. You will also receive free LED bulbs, smart power strips, and a smart thermostat (worth $235-$575).
Within 5-7 business days, you receive a detailed report ranking insulation improvements by energy savings impact. Each recommendation includes a specific rebate amount for your home.
Your report includes a list of Mass Save approved insulation contractors in your area. Get 2-3 quotes. Only approved contractors can apply the instant rebate at installation.
The contractor performs the work (typically 1-3 days for full-home insulation) and applies the 75% rebate as an instant discount on your invoice. You pay only 25% at completion. Income-eligible customers pay $0.
Insulation is not just about energy savings. It transforms how your home feels, sounds, and performs year-round.
Even out temperatures between floors and rooms. No more freezing upstairs bedrooms or cold kitchen floors.
Proper attic insulation and air sealing prevents warm air from melting snow on your roof, which refreezes at the eaves and causes ice dams.
Dense-pack wall insulation and attic insulation dramatically reduce outside noise -- traffic, lawnmowers, and neighborhood sounds.
Air sealing reduces humid summer air infiltration and winter condensation problems. Less mold risk in attics and basements.
Insulated homes use 20-40% less heating and cooling energy. Annual savings of $400-$1,200 depending on home size and fuel type.
A well-insulated home needs a smaller heat pump, costs less to operate, and maintains comfort even at -5F. Mass Save often requires insulation before heat pump installation.
Yes. Mass Save covers 75% of the cost for all customers who pay into the Mass Save programs through their electric utility (Eversource, National Grid, Unitil, or Cape Light Compact). The rebate is applied as an instant discount at installation -- your invoice shows only the 25% you owe. There is no maximum dollar cap on standard insulation rebates. Income-eligible households (at or below 60% SMI or enrolled in utility discount rate) receive 100% coverage.
Absolutely -- and Mass Save often requires it. A well-insulated home means a smaller heat pump (saving $2,000-$5,000 on equipment), lower operating costs (20-30% less electricity), and better comfort at extreme temperatures. Many Mass Save contractors will not install a whole-home heat pump until insulation and air sealing meet minimum standards. The whole-home rebate tier ($2,650/ton) requires a Manual J load calculation, and your heating load drops significantly with proper insulation.
Windows are almost never the best investment compared to insulation. A typical window replacement costs $15,000-$30,000 and saves far less energy than a $4,000-$8,000 insulation project (which you only pay 25% of). Mass Save assessors consistently recommend insulation and air sealing first. Air sealing around existing windows is highly effective and included in the 75% rebate. If windows are truly the problem, storm windows (exterior or interior) are a much more cost-effective first step.
The federal Section 25C energy efficiency tax credit expired December 31, 2025. There is no federal tax credit for insulation or weatherization in 2026. The Mass Save 75% rebate is your primary incentive. For income-eligible households, Mass Save covers 100% of the cost.
Yes. A free Home Energy Assessment is required before receiving any insulation rebates. The assessment identifies exactly what insulation measures your home needs, quantifies air leakage with a blower door test, and determines your specific rebate amounts. Call 866-527-7283 or schedule online at masssave.com.
Most insulation jobs take 1-2 days. Attic insulation (blown-in) typically takes 3-6 hours. Wall insulation (dense-pack cellulose) takes 1-2 days depending on home size. Air sealing can be done in a few hours. Basement insulation with spray foam takes about a day. If you do everything at once, expect 2-3 days total.
Dense-pack cellulose wall insulation is minimally invasive. Contractors drill small holes (about 2.5 inches) through exterior siding, blow in the cellulose under pressure, then patch and paint the holes. The result is virtually invisible on clapboard, vinyl, and wood siding. For brick or stucco, they may drill from the interior drywall instead.
No. Mass Save insulation rebates require the work to be performed by a Mass Save approved insulation contractor. The rebate is applied as an instant discount at installation -- the contractor handles all paperwork. DIY insulation does not qualify for any Mass Save rebate.
Mass Save rebates cover both types. Blown-in fiberglass or cellulose is most common for attics and walls -- it is cost-effective and performs well. Spray foam (closed-cell) is typically used for rim joists, crawlspaces, and areas needing moisture resistance. Your assessment report will recommend the best type for each area of your home.
Yes -- and Mass Save often requires insulation improvements before or alongside a heat pump installation. Properly insulated homes need a smaller (cheaper) heat pump, reduce operating costs, and maintain more even temperatures. Many contractors recommend doing insulation first, then right-sizing the heat pump to your improved building envelope.
Yes. The 75% rebate is available to all Mass Save customers regardless of income. If you pay an electric bill to Eversource, National Grid, Unitil, or Cape Light Compact, you qualify. Income-eligible households (at or below 60% State Median Income) receive 100% coverage -- completely free insulation.
Mass Save offers limited window incentives, but insulation is far more cost-effective. A $5,000 insulation project (at 75% off you pay $1,250) will save more energy than $15,000 in new windows. Mass Save assessors almost always recommend insulation and air sealing before window replacement.
See your insulation savings before you commit. The Home Energy Assessment is free, takes 2-4 hours, and comes with $235-$575 in free instant upgrades.
Your assessment report shows exactly what your home needs, what it costs, and what Mass Save covers. No obligation.
Free assessment for all Massachusetts utility customers. Serving the entire state.
