Foundation repair is a capital improvement in most cases, not a currently deductible repair. Federal tax rules treat the foundation as a major structural component of the building, so work that stabilizes, underpins, or restores it almost always has to be capitalized and added to your home’s tax basis. That higher basis reduces your taxable gain when you eventually sell.
The catch is that “in most cases” does real work in that sentence. Patching a hairline crack is not the same project as driving steel piers to bedrock, and the tax treatment follows the scope of the job.
How the IRS Draws the Line Between a Repair and an Improvement
Under 26 CFR ยง 1.263(a)-3, an expenditure on property has to be capitalized if it meets any one of three tests: betterment, restoration, or adaptation.1eCFR. 26 CFR 1.263(a) – Capital Expenditures
- Betterment covers work that fixes a material defect that existed before you bought the property, physically enlarges the property, or materially increases its strength, capacity, or quality.
- Restoration covers returning the property to working condition after a major component has deteriorated or failed, or replacing a substantial structural part of the building.
- Adaptation covers converting the property to a use different from its original purpose.
An expense that clears none of these tests is a deductible repair for the current year. The betterment test specifically reaches work that “ameliorates a material condition or defect that either existed prior to the taxpayer’s acquisition” or is “reasonably expected to materially increase the productivity, efficiency, strength, quality, or output of the unit of property.”2eCFR. 26 CFR 1.263(a)-3 – Amounts Paid to Improve Tangible Property The IRS treats the building structure, including its foundation, as a distinct unit of property, which is why foundation work gets analyzed against these tests as a whole.
Foundation Projects That Qualify as Capital Improvements
Because the foundation holds up everything above it, substantial repair work generally satisfies the restoration test: you are returning a major structural component to safe, functional condition after deterioration. The kinds of projects that qualify include:
- Installing steel piers to stabilize a sinking foundation.
- Underpinning with helical piers.
- Injecting high-density polyurethane foam to lift a settled slab.
These interventions change the structural capacity of the building and are designed to last the life of the structure. The costs get added to basis.1eCFR. 26 CFR 1.263(a) – Capital Expenditures
There is a separate path to the same result if you bought a home that already had a foundation problem and then paid to fix it. That work can qualify under the betterment test, because it corrects a material defect that predated your ownership. The cost is still capitalized.2eCFR. 26 CFR 1.263(a)-3 – Amounts Paid to Improve Tangible Property
What Stays a Deductible Repair
Filling a hairline crack with epoxy or patching minor surface damage does not change the structural capacity of the building. That kind of cosmetic or maintenance work stays in the repair column and is deducted in the year you pay for it, not added to basis. The permanence of the fix matters too. Temporary shoring that will be removed is harder to classify as a capital improvement; permanent piering fits squarely within the restoration framework.
A practical marker: once you are hiring a structural engineer, pulling permits, and installing hardware meant to stay in place, you have crossed into capital improvement territory.
What the Classification Actually Saves You
Adding foundation costs to basis matters at sale, but on a primary residence, most owners never feel it. Section 121 of the Internal Revenue Code lets you exclude up to $250,000 of gain if you are single, or up to $500,000 if you are married filing jointly, provided you owned and used the home as your primary residence for at least two of the five years before the sale. The exclusion is available once every two years.3Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence
If your total gain falls inside that exclusion, the foundation repair does not change your tax bill. Where the basis adjustment starts paying off is when your gain exceeds the exclusion threshold, which is a real possibility for long-time owners in high-appreciation markets. A $20,000 foundation project added to basis reduces taxable gain by $20,000. At a 15% long-term rate, that is $3,000 in tax saved on the portion of gain above the exclusion.
IRS Publication 523 lays out the calculation: subtract your adjusted basis (original purchase price plus capital improvements like foundation work, minus any depreciation taken) from the sale price to determine your gain, then apply the exclusion.4Internal Revenue Service. Publication 523 (2025), Selling Your Home
Rental and Investment Property Works Differently
There is no Section 121 exclusion for property you do not live in as your primary residence, so on a rental, the basis adjustment from foundation work reduces taxable gain dollar for dollar at sale. But you cannot simply park the cost on your basis and wait. Structural capital improvements on residential rental property must be depreciated over 27.5 years under the Modified Accelerated Cost Recovery System (MACRS). The improvement is treated as a separate depreciable asset placed in service on its completion date, using the same 27.5-year recovery period as the underlying building.5Internal Revenue Service. Publication 527 (2025), Residential Rental Property A $20,000 foundation stabilization on a rental produces roughly $727 per year in depreciation.
Depreciation that you take, or that you were entitled to take, reduces your adjusted basis. When you sell, the portion of your gain attributable to depreciation is “recaptured” and taxed as ordinary income rather than at long-term capital gains rates. Skipping the annual deduction does not spare you from recapture, because the IRS calculates it on the depreciation you were entitled to claim, whether you actually claimed it or not.
Insurance Proceeds Change the Math
If your homeowner’s insurance pays part of the foundation bill, you cannot capitalize the full cost. The IRS requires you to reduce your basis by the amount of insurance proceeds you receive, and only the out-of-pocket amount you actually spent gets added to basis as an improvement.6Internal Revenue Service. Tangible Property Final Regulations
Say a stabilization job costs $18,000 and your insurer pays $7,000. You reduce basis by the $7,000 payment, then add the remaining $11,000 you paid yourself as a capital improvement. Standard homeowner’s policies typically exclude foundation settlement and movement, so most owners bear the whole cost, but if a covered event like a plumbing leak triggered the damage, a payout is possible.
Records to Keep Now
Basis questions do not surface until you sell, which could be decades after the foundation work is done. Your paperwork has to last that long. For every foundation project you plan to capitalize, keep:
- Itemized contractor invoices showing materials, labor, and the specific structural work performed. A single lump-sum invoice is not ideal if the project bundled capitalizable structural work with incidental cosmetic repairs.
- The written scope of work from the foundation specialist or structural engineer describing the engineering requirements and the nature of the stabilization. This is your strongest evidence that the project went beyond routine maintenance.
- Building permits issued by your local authority, which confirm the work required regulatory oversight.
- Proof of payment: bank statements, canceled checks, or credit card records showing amounts paid to the contractor.
- Engineering reports or inspections documenting the condition of the foundation before and after the work.
Professional fees paid to structural engineers and architects for work directly tied to the project also get added to basis.7Internal Revenue Service. Publication 551 (2025), Basis of Assets If you paid an engineer $2,000 to design the pier layout and a contractor $18,000 to install the piers, your total capitalizable cost is $20,000. Track those fees separately so nothing gets missed when you eventually sell.