Insulation and Air Sealing Tax Credit: Line 18 on Form 5695

Insulation and air sealing installed by December 31, 2025 qualify for a federal tax credit: 30% of your costs, up to $1,200. No QMID required for this one.

This credit goes on Form 5695, Part II, Section A, Line 18. It's separate from the heat pump credit and uses different rules.

Credit Amount

You can claim 30% of what you spent on insulation materials and air sealing systems. The maximum is $1,200 per year.

Example calculation:

• Insulation project cost: $5,000
• 30% of $5,000: $1,500
• Credit (capped): $1,200

For a smaller project:

• Insulation cost: $3,000
• 30% of $3,000: $900 (no cap applies)

What Qualifies

The insulation must meet IECC (International Energy Conservation Code) standards. Most commercially sold insulation meets these requirements, but verify with your contractor before purchase.

IECC Standards

IECC standards specify minimum R-values (thermal resistance) for insulation based on climate zone. Your contractor should know your area's requirements.

Common IECC-compliant insulation R-values:

• Attic insulation: R-30 to R-60 (depending on climate)
• Wall insulation: R-13 to R-21
• Floor insulation: R-25 to R-30
• Basement walls: R-10 to R-15

Air sealing products must be specifically designed to reduce air leakage and heat loss. Standard maintenance products don't qualify.

No QMID Required

Unlike heat pumps, windows, or doors, insulation doesn't require a QMID (Qualified Manufacturer Identification Number).

Form 5695 Line 18 has two simple fields:

• 18a: Enter your total insulation and air sealing costs
• 18b: Calculate 30% of Line 18a (max $1,200)

No manufacturer codes, no certification numbers. Just costs and calculation.

How to Claim It

Section A Qualifying Questions

Before claiming insulation credits, you must answer Form 5695 qualifying questions on Lines 17a through 17e.

Line 17a: Were the improvements installed in your main home in the United States?

Answer "Yes" if the insulation was installed in your primary residence. Second homes and rental properties don't qualify for building envelope improvements.

Line 17b: Are you the original user of the property?

Answer "Yes." The credit only applies to new insulation you installed, not insulation that was already in the home when you bought it.

Line 17c: Will the components remain in your home for at least 5 years?

Answer "Yes." You're certifying that you installed the insulation permanently, not as a temporary measure.

Line 17d: Main home address

Enter the address where you installed the insulation. If it's the same as your filing address, you can write "Same as filing address."

Line 17e: Were the improvements related to construction of this home?

If you're building a new home, answer "Yes" and only post-construction improvements qualify. For existing home retrofits, answer "No."

Labor Costs Included

Unlike some energy credits, the insulation credit covers both materials and labor.

If your contractor charged:

• Materials: $2,000
• Labor: $1,500
• Total eligible cost: $3,500
• Credit (30%): $1,050

This is a significant benefit. Labor can be 30-40% of total insulation project costs.

The $1,200 Annual Cap

The $1,200 limit for insulation is part of a larger $1,200 annual cap that includes:

• Insulation and air sealing (Line 18)
• Exterior doors (Line 19, max $500)
• Windows and skylights (Line 20, max $600)
• Central AC (Line 22, max $600)
• Gas/oil water heaters (Line 23, max $600)
• Furnaces and boilers (Line 24, max $600)
• Electrical panel upgrades (Line 25, max $600)
• Home energy audits (Line 26, max $150)

Form 5695 Line 28 enforces this cap. Even if your individual credits add up to more than $1,200, Line 28 caps the total at $1,200.

Example:

• Insulation credit (Line 18b): $900
• Window credit (Line 20d): $600
• Total before cap: $1,500
• Line 28 (capped): $1,200

Heat pumps and heat pump water heaters (Line 29) are NOT part of this $1,200 cap. They have their own $2,000 annual limit.

Credit Expiration

The installation date determines eligibility, not the filing date.

• Installed December 2025: Eligible (claim on 2025 return)
• Installed January 2026: Not eligible

Combining with Other Credits

You can claim insulation credits alongside other Form 5695 credits in the same year.

Scenario: You installed insulation and a heat pump in 2025.

• Insulation cost: $4,000
• Insulation credit (30%, max $1,200): $1,200 (Line 18b)
• Heat pump cost: $8,000
• Heat pump credit (30%, max $2,000): $2,000 (Line 29h)
• Total credit (Line 30): $3,200

The insulation credit doesn't reduce your heat pump credit. They stack up to the combined annual limit of $3,200.

Non-Refundable Credit

The 25C credit is non-refundable. It reduces your tax liability but won't generate a refund beyond what you've already paid.

Plan accordingly. If you typically get large refunds (meaning you've overpaid through withholding), you'll likely use the full credit.

Common Mistakes

Record Keeping

Keep these documents for at least 3 years after filing:

• Contractor invoice with installation date and itemized costs
• Product specifications (R-values, IECC compliance)
• Payment records
• Photos of work (optional but helpful)

The IRS can audit returns up to 3 years after filing. Clean records prevent issues.

Using Tax Software

Most tax software handles Form 5695 automatically. Look for:

• "Energy efficient home improvement"
• "Residential energy credit"
• "Insulation credit"

Enter your costs and the software calculates the credit, applies caps, and transfers the final amount to Schedule 3.

Official Resources