Why Untracked Home Renovations Could Cost You Thousands When You Sell
If you've put money into your home over the years, a kitchen remodel, an addition, a new roof, and you haven't kept the receipts, you may be sitting on a much bigger tax bill than you need to when you sell. The IRS lets you add the cost of capital improvements to your home's "basis," which directly reduces your taxable gain. If you can't document those costs, you lose that reduction, even though the money was genuinely spent. (See IRS Publication 523, Selling Your Home, for the full rules.)
I see this constantly with clients in Newport Beach and Corona del Mar who've owned their home for 10, 15, 20 years. They renovated in phases, paid contractors from different accounts, never filed anything away, and now they're sitting on a home worth two or three times what they paid for it. When we sit down to actually calculate the gain, the receipts they don't have are worth real money.
Who this is for: homeowners who've done any meaningful renovation work and plan to sell eventually, especially in a high-appreciation market like coastal Orange County.
Key takeaways
Your home's basis isn't just what you paid for it. Capital improvements, not repairs, get added to basis and reduce your taxable gain dollar for dollar.
There's a federal exclusion on the gain from selling a primary residence if you meet ownership and use requirements, but it's capped, and California taxes any gain above it as ordinary income with no special rate.
Without receipts or records, the IRS has no obligation to accept your estimate of what you spent. You need documentation, not memory.
What actually counts as a capital improvement?
This is where most of the confusion starts, so it's worth being precise. A capital improvement adds value to your home, extends its useful life, or adapts it to a new use. A kitchen remodel, a room addition, a new roof, a pool, central air installation, a finished basement, a new HVAC system. These all count, along with architect fees, permit costs, and the labor involved.
A repair, on the other hand, keeps your home in its normal operating condition without adding value. Painting a room, fixing a leaky faucet, patching drywall, replacing a broken window pane. These are maintenance, and they don't get added to basis no matter how much they cost.
The line gets blurry in practice. Replacing a broken water heater on its own is a repair. Replacing it as part of a full renovation of the plumbing system is generally treated as part of the capital improvement. When work is bundled into a larger renovation, I treat the whole project as capital improvement and document it that way, in line with how IRS Topic No. 703 frames basis adjustments.
How do you actually calculate your adjusted basis?
Your basis starts as your original purchase price, plus certain closing costs (title insurance, legal fees, transfer taxes you paid as the buyer). From there, you add the cost of every capital improvement over the years you've owned the home. That total is your adjusted basis (IRS Publication 523 has the full list of what qualifies).
When you sell, your gain is the sale price minus selling costs (commissions, staging, escrow fees) minus your adjusted basis. That gain, not the full sale price, is what gets measured against your exclusion.
Here's where it matters in real numbers. I worked with a couple in Corona del Mar who bought their home for $1.2 million and, over 14 years, put roughly $400,000 into a kitchen remodel, a primary suite addition, and a pool. They're now selling for $3.2 million.
With documentation of those improvements, their adjusted basis is $1.6 million. Gain: $1.6 million. Minus their married-filing-jointly exclusion, taxable gain: roughly $1.1 million.
Without documentation, their basis is just the $1.2 million purchase price. Gain: $2 million. Minus the exclusion, taxable gain: roughly $1.5 million.
That's $400,000 of additional taxable gain, purely because the receipts weren't kept. At the tax rates many high-income California households pay on gains like this, that gap alone can easily mean well over $100,000 in unnecessary tax.
The money was spent either way. The only question is whether you can prove it.
Why didn't my CPA already tell me this?
This is the question I hear most, and it's a fair one. Most CPA relationships are built around tax preparation, not tax planning. Your CPA sees your numbers once a year, months after the renovation is finished, and their job at that point is to file an accurate return with the information you give them. If you don't bring up a kitchen remodel from three years ago, there's nothing prompting them to ask.
This is exactly the gap that shows up when tax and financial planning are handled by two separate people who only talk once a year, if at all. As someone who works with clients as both their CPA and their CFP®, I bring this up during the renovation, not after the sale, because that's when it's actually useful. Waiting until you're preparing to sell to think about basis is usually waiting too long to reconstruct records that should have been kept in real time.
What records should you actually keep?
For every capital improvement, keep the contractor invoice, proof of payment (bank or credit card statement showing the transaction), and the permit if one was pulled. A folder, physical or digital, labeled by project and year is enough. Scan paper receipts; they fade.
Keep these records for as long as you own the home, plus several years after you sell, in case of an audit. The exact recommended window is worth confirming with your CPA, since it ties to the statute of limitations on the return reporting the sale.
If you've already done renovations without saving anything, it's not always a lost cause. Contractor invoices can sometimes be requested after the fact, permit records are often searchable through your city, and large purchases may show up on old bank or credit card statements.
What if you claimed a home office or rented part of the house?
If you're self-employed and took a home office deduction, or you rented out part of the property, this adds a layer. Any depreciation you claimed reduces your basis, so you don't get to add improvements on top of a basis that hasn't been adjusted down for depreciation already taken. That depreciation is also typically taxed separately at sale, usually at a less favorable rate than standard long-term capital gains (Publication 523 and Topic No. 703 both cover how this is calculated).
This is a case where the interaction between your business tax return and your home sale can genuinely change the outcome, and it's worth running the actual numbers before you list the property.
How does this work differently in California?
Federally, long-term capital gains get a preferential rate. California doesn't do this: it taxes capital gains as ordinary income, on the same brackets as your salary. The California Franchise Tax Board publishes the current rate structure and conformity rules for the home sale exclusion.
That means the stakes of getting your basis calculation right are higher here than in most states. A homeowner in a no-income-tax state loses less by underreporting their basis than someone in California does. If you're selling an appreciated home in Newport Beach or Corona del Mar, the gap between a documented basis and an undocumented one is worth meaningfully more in after-tax dollars than the same gap would be almost anywhere else.
If you're planning to sell an appreciated home, it's worth having your basis calculation reviewed before you list it. Reach out to Katherine to make sure you're not leaving money on the table.
When does it make sense to work with a financial planner on this?
Usually well before you list the house. If your home has appreciated significantly, if you've done more than one or two renovation projects over the years, or if you've used part of the home for business, it's worth having your basis reviewed while you still have time to track down documentation, not after you've already signed a listing agreement.
This is also a good moment to look at the sale in the context of your full financial picture: what the proceeds are earmarked for, whether the timing affects your other income for the year, and how the gain interacts with anything else happening in your tax picture that year.
FAQ
Do home improvements reduce capital gains tax?
Yes. Capital improvements, projects that add value or extend the life of your home, get added to your cost basis, which directly reduces your taxable gain when you sell. Repairs and routine maintenance don't count. See IRS Publication 523 for the full definitions.
What records do I need to prove my home's basis?
Keep contractor invoices, proof of payment, and permits for every capital improvement, organized by project and year. Bank and credit card statements can help substantiate payments if you're missing an invoice.
How much capital gains exclusion do I get on my primary residence?
There's a federal exclusion available if you meet ownership and use requirements, with a higher amount for married couples filing jointly than for single filers. IRS Publication 523 has the current thresholds and qualifying rules.
Does California tax home sale capital gains differently than the federal government?
Yes. California taxes capital gains as ordinary income with no special lower rate, unlike the federal system. The California Franchise Tax Board publishes the current rate structure.
What if I don't have receipts for renovations I did years ago?
Try requesting duplicate invoices from contractors, searching city permit records, and reviewing old bank and credit card statements. It's more work than keeping records as you go, but it can often recover a meaningful amount of basis.
Summary
Capital improvements, not repairs, get added to your home's basis and directly reduce your taxable gain at sale
There's a federal exclusion on gain from selling a primary residence, but it's capped, and California taxes gain above it as ordinary income with no special rate
Without documentation, undocumented improvements effectively don't exist for tax purposes
Most CPA relationships are built around annual filing, not real-time planning, which is why renovation record-keeping often falls through the cracks
Keep contractor invoices, proof of payment, and permits for every project, organized as you go
Home office use or rental history adds a depreciation adjustment that changes the calculation
Review your basis calculation before you list the house, not after
Author bio: Katherine Leonard, CPA, CFP®, helps individuals, business owners, and families integrate tax planning with comprehensive wealth planning throughout California.
Sources cited: IRS Publication 523 — Selling Your Home, IRS Topic No. 703 — Basis of Assets, California Franchise Tax Board