A new AC unit is not directly tax deductible in the way charitable donations or mortgage interest are, but federal law offers several tax benefits depending on the equipment and how you use the property. The most common is the Energy Efficient Home Improvement Credit under Section 25C, worth up to $600 for a qualifying central air conditioner or up to $2,000 if you install a heat pump. Beyond that, a new system may generate a medical expense deduction, rental depreciation, a home office deduction, or an increase in your home’s cost basis that reduces capital gains when you sell.
The Federal Energy Credit for a New Central AC
Section 25C of the Internal Revenue Code gives homeowners a credit equal to 30 percent of the cost of a qualifying central air conditioning system, including equipment and installation labor, capped at $600 per year for a central AC.1Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit A credit is more valuable than a deduction of the same size because it reduces your tax bill dollar for dollar rather than reducing the income the tax is calculated on.
The unit has to be installed in your principal residence, and it must carry the ENERGY STAR “Most Efficient” designation. A basic ENERGY STAR label alone does not qualify.1Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit Ask your contractor or the manufacturer to confirm the model qualifies and to provide the certification statement you will need at tax time.
What Costs Count
For central AC units and heat pumps, the 30 percent applies to your full project invoice. Labor for onsite preparation, assembly, and original installation counts.2Internal Revenue Service. Energy Efficient Home Improvement Credit – Labor Costs That rule does not extend to windows, doors, or insulation you might install in the same year, where labor is excluded.
Annual Cap and No Carryforward
The $600 AC cap sits inside a broader $1,200 annual aggregate limit covering most energy-efficient improvements such as insulation, exterior doors, and windows.1Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit The credit resets each calendar year with no lifetime cap, so spreading projects across years captures more of the benefit.
The credit is non-refundable. It can zero out what you owe but will not produce a refund, and any unused portion is lost. You cannot carry it forward.3Internal Revenue Service. Energy Efficient Home Improvement Credit – Timing of Credits If your tax liability for the year is low, the credit’s value is limited to that liability.
How to Claim It
Report the credit on IRS Form 5695 (Residential Energy Credits) and attach it to your Form 1040.4Internal Revenue Service. Instructions for Form 5695 Keep the manufacturer certification statement, the purchase receipt, and the installation invoice. One quiet consequence to note: claiming the credit reduces the basis increase this improvement would otherwise create, which affects capital gains if you sell later.1Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit
Heat Pumps Get a Higher $2,000 Credit
Install a heat pump that handles both heating and cooling, and the credit rises to 30 percent of project costs up to $2,000 per year. Qualifying units must meet or exceed the top efficiency tier set by the Consortium for Energy Efficiency.5Internal Revenue Service. Energy Efficient Home Improvement Credit Starting in 2025, eligible heat pumps must carry the ENERGY STAR Most Efficient designation, with separate criteria for cold-climate models.6ENERGY STAR. Air Source Heat Pumps Tax Credit
The $2,000 heat pump limit is separate from the $1,200 annual cap on other improvements.5Internal Revenue Service. Energy Efficient Home Improvement Credit A homeowner installing a qualifying heat pump and making other eligible upgrades in the same year could claim up to $3,200 combined. Labor and installation costs count toward the 30 percent calculation.2Internal Revenue Service. Energy Efficient Home Improvement Credit – Labor Costs
When AC Counts as a Medical Expense
If a physician determines air conditioning is medically necessary — typically for severe asthma, chronic respiratory disease, or serious allergies — the cost may be deductible as a medical expense under Section 213. This is an itemized deduction on Schedule A, and it requires a written recommendation from your doctor stating the system is needed to treat or manage your condition.7Internal Revenue Service. Publication 502, Medical and Dental Expenses
You cannot deduct the full cost. Subtract the amount the installation adds to your home’s value. If a $12,000 system raises property value by $8,000, only $4,000 counts as a medical expense. That $4,000 combines with your other medical costs, and only the total exceeding 7.5 percent of your adjusted gross income is deductible.7Internal Revenue Service. Publication 502, Medical and Dental Expenses At a $100,000 AGI, medical costs would need to exceed $7,500 before any benefit appears.
Once the system is installed, the electricity and maintenance costs to run it also qualify as medical expenses, even if the original installation was fully offset by the increase in home value.7Internal Revenue Service. Publication 502, Medical and Dental Expenses Track those utility and service costs separately each year for Schedule A.8Internal Revenue Service. Instructions for Schedule A – Itemized Deductions
Rental Property: Depreciation, Not a One-Year Write-Off
For a rental property, a new AC unit is a capital improvement. You recover the cost through depreciation over 27.5 years using the straight-line method under MACRS.9Internal Revenue Service. Publication 527, Residential Rental Property A $10,000 system yields roughly $364 per year against rental income.10Internal Revenue Service. Publication 946, How To Depreciate Property
Section 179 expensing, which lets certain businesses deduct the full cost of qualifying equipment in the year of purchase, does not apply to HVAC in residential rental property. Once the AC becomes a structural component of a residential building, it inherits the building’s 27.5-year classification. Section 179 does reach HVAC improvements in nonresidential real property such as commercial buildings, but not houses, apartments, or other dwellings where 80 percent or more of rental income comes from residential tenants.9Internal Revenue Service. Publication 527, Residential Rental Property
A small-taxpayer safe harbor can let you deduct the full cost in the installation year. It is available if the property’s unadjusted basis is $1 million or less, and total annual repair, maintenance, and improvement expenses for the building do not exceed the lesser of $10,000 or 2 percent of the unadjusted basis.11Internal Revenue Service. Tangible Property Final Regulations On a $300,000 basis, the threshold is $6,000. Exceed that, and you fall back to 27.5-year depreciation for the entire cost.
Home Office Portion for the Self-Employed
If you are self-employed and use part of your home exclusively and regularly as your principal place of business, a share of a new central air system can become a business deduction. The share matches the percentage of the home used for the office. A home office occupying 15 percent of the square footage means 15 percent of the AC cost is a business expense.
Under the regular (actual expense) method, that business portion is depreciated over 39 years, not deducted at once.12Internal Revenue Service. Publication 587, Business Use of Your Home Section 179 cannot be used to expense the business portion of improvements to your home. The simplified method, which pays a flat rate per square foot up to 300 square feet, does not allow any depreciation for home improvements.13Internal Revenue Service. Simplified Option for Home Office Deduction To claim part of a major improvement like a new AC, the regular method is the only route.
The Basis Benefit When You Sell
Even without a credit or deduction at installation, a new central air system helps when you sell the home. IRS Publication 523 lists central air conditioning as a capital improvement that increases the cost basis.14Internal Revenue Service. Publication 523, Selling Your Home A higher basis means a smaller taxable gain.
Buy a home for $300,000, add a $10,000 AC, and the adjusted basis rises to $310,000. Sell for $500,000, and the gain is $190,000 rather than $200,000. This matters most when the gain exceeds the home sale exclusion of $250,000 for single filers or $500,000 for joint filers.15Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence If you claimed the Section 25C credit on the same system, the credit reduces the basis increase. A $600 credit on a $10,000 system adds $9,400 to basis, not the full $10,000.1Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit
Keep receipts, contractor invoices, and installation contracts for at least three years after the due date of the return for the year you sell.14Internal Revenue Service. Publication 523, Selling Your Home Holding them for as long as you own the property is safer, since sale timing is rarely predictable.
State and Utility Rebates
Federal tax benefits are not the only pool. Many states and local utilities offer rebates for energy-efficient HVAC. The federally funded High-Efficiency Electric Home Rebate Act (HEEHRA) provides point-of-sale discounts for heat pump systems based on household income, up to $8,000 for households earning less than 80 percent of area median income and up to $4,000 for those between 80 and 150 percent. Programs are administered by individual states and availability varies. Check your state energy office or the ENERGY STAR rebate finder for what is active in your area. These rebates can generally be combined with the federal Section 25C credit, though they may reduce the project cost used to calculate the credit.