The Alarm Date Stamp That Can Hold Up Your Closing

Bob Wiltse

3 days ago

6 min read

Check your smoke and carbon monoxide alarms.

Bob Wiltse, REALTOR®

Research & Writing Assistant: Claude.ai

October 26, 2026

Clocks fall back this Sunday, November 1, a good weekend to check your smoke and carbon monoxide alarms. If you plan to sell, know that Massachusetts requires a smoke and CO certificate from your local fire department to close.

Place alarms on every level, at the base of stairs, and outside sleeping areas. Newer homes also need one inside each bedroom.

Why it matters

Carbon monoxide (CO) is a gas you can't see or smell. It forms whenever fuel burns: furnaces, boilers, water heaters, fireplaces, generators, and cars. An old alarm, the wrong type, or one in the wrong spot can cause a failed inspection, a reinspection fee, and a scramble the week you close.

What to look for

The date stamp. Every alarm has a manufacture date on the back or side. Replace smoke alarms over 10 years old. DFS says an alarm with no date counts as expired.
The type. Look for the word "photoelectric" on the label. Many Massachusetts rules now call for photoelectric alarms.
Power. Is it battery-only or hardwired (wired into the home's electrical system) with a battery backup?
Coverage. Alarms on every level, at the base of stairs, and outside sleeping areas. Newer homes also require one inside each bedroom.
CO alarms. Install one on every level and within 10 feet of each bedroom door in any home with fuel-burning equipment or an attached garage.
The garage. Homes built or permitted since 2008 need a heat alarm in an attached garage.

Smoke and CO alarm types and what they do

Photoelectric smoke alarms use a light beam to sense smoke. They're less prone to false alarms from cooking or shower steam.
Ionization smoke alarms react quickly to flaming fires but are more likely to go off near kitchens and baths. Massachusetts limits where they can be used.
Combination smoke/CO alarms do both jobs in one unit. DFS limits ionization/CO combos to within 20 feet of a kitchen or full bath. Combos must include both a tone and a voice warning.
10-year sealed-battery alarms have a nonremovable battery; you replace the whole unit. Massachusetts requires them for new or replacement battery-powered smoke alarms.
Hardwired, interconnected alarms run on house power with battery backup. When one sounds, they all sound.
Wireless interconnected alarms link by radio. In post-1975 homes they still need house power.
Monitored systems connect to a panel. The inspector will need it put in test mode.

Questions to ask before the smoke and CO certificate inspection

To the seller: When were the alarms last replaced? Do you have receipts or an electrician's invoice?
To the seller: Has the home had renovation permits? (That can change which rules apply.)
To the fire department: Which requirements apply to this home, based on its age and permits?
To the fire department: How far in advance should I book, what's the fee, and how long is the certificate valid?
To your home inspector: Did you note any missing, expired, or painted-over alarms?
To an electrician: Will replacement alarms work with the existing wiring and interconnect?

Red flags

No date on the alarm, or a date more than 10 years ago
Alarms painted over, unplugged, or with batteries pulled
A finished basement or attic room with no smoke or CO alarm
Fuel-burning equipment but no CO alarm nearby
An alarm that's been "chirping" for weeks

If you're buying / If you're selling

If you're buying: The seller gets the certificate. It’s required in order to close.

If you're selling: Book the inspection as soon as you have a closing date. Check every date, replace expired alarms with the right type, and use a licensed electrician for hardwired alarms. Give the original certificate to your closing attorney. Your real estate agent will guide you.

The Massachusetts angle: how the smoke and CO certificate works

Code: M.G.L. c. 148 § 26F requires smoke alarms when a home is sold, and § 26F½ (Nicole's Law) requires CO alarms in homes with fuel-burning equipment or enclosed parking, with a fire department inspection at sale or transfer. The local fire department issues the certificate when both pass.

Code: Requirements depend on when the home was built or last substantially renovated. DFS sorts homes into eras (before 1975, 1975–1997, after Aug. 27, 1997, 2008+, and Feb. 4, 2011+). Newer eras add hardwiring, interconnection, bedroom alarms, and an all-photoelectric rule.

Local rules: Towns set fees, scheduling, and certificate validity. In Concord, a single-family inspection costs $50, and the certificate is valid for 60 days.

Best practice: Test alarms monthly. Service fuel-burning appliances before winter and keep vents clear of snow, as DFS advises.

Watch for changes: On Oct. 15, 2026, the state fire board voted to begin amending the fire code (527 CMR 1.00). Nothing has changed yet.

Your town may have stricter rules. Cities and towns choose their energy code tier, and many have local bylaws, board of health regulations, zoning, and building and fire department policies that go beyond state code. Always check with your local building department, board of health, or fire department.

Bottom line

The smoke and CO certificate is easy to get right and frustrating to get wrong. Check the dates, check the types, cover every level, and call the fire department early.

FAQ

Do I need a smoke and CO certificate to sell a house in Massachusetts? Yes. State law requires the local fire department to check smoke and carbon monoxide alarms when a home is sold or transferred. If the alarms pass, the department issues a certificate of compliance, which is usually needed at closing. Schedule the inspection as soon as you have a closing date.

How old can smoke alarms be and still pass? Smoke alarms can't be more than 10 years old, or past the maker's stated life, whichever comes first. Check the manufacture date on each alarm. DFS says an alarm with no date counts as expired and must be replaced. CO alarms often last 5 to 7 years; follow the manufacturer's date.

Do smoke alarms have to be hardwired in Massachusetts? It depends on when the home was built or last permitted. Homes built before 1975 may use battery alarms, but new or replacement battery alarms must have 10-year sealed batteries. Homes built since 1975 generally need hardwired, interconnected alarms. Ask your fire department which rules apply to your home.

How long is the certificate good for? That's set locally. Concord and Wellesley, for example, say their certificates are good for 60 days. If your closing date moves, check whether your certificate will still be valid. Call your local fire department for its rules and fees.

Where do carbon monoxide alarms go? DFS guidance calls for CO alarms on every level of the home, including habitable basements and attics, and within 10 feet of each bedroom door. Combination smoke/CO units are allowed in many cases. Don't put CO alarms in garages or right next to stoves or fireplaces.

Buying or selling a home in Massachusetts? I help buyers know what they're looking at and help sellers get their homes market-ready. Call or text me at 978-793-1719, or visit bobwiltse.com.

Disclaimer: This article is general information, not professional engineering, legal, health, or code-compliance advice. Codes change and vary by town. Consult licensed professionals and your local building department, board of health, or fire department before making decisions about your home.