The Biggest Tax Deduction Mistakes Homeowners Make Every Year

Fact-checked by the The Finance Tree editorial team

Every spring, millions of homeowners sit down to file their taxes and leave hundreds — sometimes thousands — of dollars on the table. Homeowner tax deduction mistakes are shockingly common, and the IRS isn’t going to send you a reminder that you missed something. According to the IRS Taxpayer Advocate Service, the tax code contains over 200 tax expenditures — credits and deductions — and the average filer fails to claim several they legitimately qualify for. For homeowners specifically, that oversight can mean paying far more than necessary on a return that should be working in their favor.

The numbers are staggering. The Urban Institute’s tax expenditure analysis estimates that the mortgage interest deduction alone was worth over $25 billion in tax savings to homeowners in a single year — yet many filers either claim it incorrectly or don’t claim it at all. Meanwhile, the IRS estimates that taxpayers collectively overpay by billions annually due to missed deductions. A 2022 survey by the National Association of Tax Professionals found that more than 40% of self-prepared returns contained at least one deduction error. For homeowners, those errors tend to cluster around specific, avoidable mistakes.

This guide breaks down the most costly and most common homeowner tax deduction mistakes in clear, actionable detail. You’ll learn which deductions are misunderstood, which are frequently skipped, and exactly how to make sure your tax return captures every dollar you’re legally owed. Whether you file with software or hire a professional, the knowledge here could save you thousands.

Mortgage Interest Deduction Errors That Cost You Most

The mortgage interest deduction is one of the largest tax benefits available to homeowners — and one of the most frequently botched. Under current law, you can deduct interest paid on up to $750,000 of mortgage debt on your primary or secondary home. For loans originated before December 15, 2017, the older $1,000,000 limit still applies.

One of the most common errors is failing to deduct interest at all because a homeowner assumes their loan balance is too high. But the limit applies to the debt principal, not the home’s value — and the deduction is still available on the first $750,000 even if your loan exceeds that amount. Misunderstanding this rule leaves real money on the table.

Missing Form 1098 Information

Lenders are required to send Form 1098 to every borrower who paid $600 or more in mortgage interest during the year. Many homeowners misplace this form or forget to enter its data into their tax return. Without it, they either skip the deduction entirely or enter an estimate that doesn’t match IRS records.

If you have multiple loans — say, a primary mortgage and a second mortgage — you should receive a separate Form 1098 for each. Failing to account for all of them is a significant homeowner tax deduction mistake that triggers both missed deductions and potential notices from the IRS when they cross-reference lender-reported data.

Deducting Points Incorrectly Over the Loan Life

When you pay mortgage points at closing, you may be able to deduct them — but the rules differ depending on whether the loan is for a purchase or a refinance. Points paid on a home purchase are generally fully deductible in the year paid. Points paid on a refinance must be amortized over the life of the loan.

Homeowners who refinanced and then refinanced again often forget to deduct the remaining un-amortized points from the first refinance in the year they pay off that loan. That’s an entirely legal deduction that disappears if you don’t know to claim it.

Property Tax and SALT Deduction Mistakes

The State and Local Tax (SALT) deduction allows homeowners to deduct up to $10,000 in combined state income taxes, local income taxes, and property taxes. This cap was introduced by the Tax Cuts and Jobs Act of 2017 and remains in place through at least 2025. For homeowners in high-tax states like California, New York, or New Jersey, this $10,000 limit is frequently hit — yet many still calculate it incorrectly.

One overlooked error is deducting property taxes that weren’t actually paid during the tax year. Escrow accounts often create timing confusion — your lender may pay your county tax bill in January for the prior year, meaning the actual payment falls in a different tax year than you expect.

Confusing Assessments with Tax Bills

Homeowners sometimes deduct their annual property tax assessment figure rather than the actual tax they paid. These numbers can differ significantly. Special assessments — charges for local improvements like sidewalks or drainage systems — are generally not deductible as property taxes, even though they appear on the same bill.

The IRS is explicit: only ad valorem taxes (taxes based on the assessed value of your property) qualify for the SALT deduction. Fees for specific services do not. Mixing these up is a common homeowner tax deduction mistake that could trigger an audit.

Timing Errors with Escrow Payments

If your property taxes are paid through an escrow account, you can only deduct them in the year your lender actually remits payment to the taxing authority — not when you made escrow deposits. Check your Form 1098, which lenders are now required to report escrow disbursements on, to confirm the correct year.

The Overlooked PMI Deduction

Private Mortgage Insurance (PMI) is the monthly premium paid by homeowners who put down less than 20%. For years, this deduction was on-again, off-again — Congress repeatedly allowed it to expire and then reinstated it retroactively. As of the latest tax legislation, PMI premiums paid by qualifying homeowners are deductible as mortgage interest.

The deduction phases out for households with adjusted gross income (AGI) above $100,000, disappearing entirely at $109,000 for single filers and married filers alike. For those under the threshold, the deduction can be worth $500 to $1,200 per year depending on loan size and PMI rate.

Who Misses This Deduction Most Often

First-time homeowners with FHA loans are among the most likely to miss the PMI deduction. FHA loans charge an upfront mortgage insurance premium (MIP) plus an annual MIP — both of which may be deductible under the same rules as PMI. Homeowners who financed their upfront MIP into the loan also need to amortize that portion over the loan life, similar to how points work on a refinance.

Because the deduction’s status has fluctuated legislatively, many tax software programs don’t prompt users to enter PMI amounts in the most intuitive place. It’s easy to skip without realizing the program expects you to enter it under mortgage interest supplemental fields on Schedule A.

Home Office Deduction Pitfalls

The home office deduction is simultaneously one of the most valuable and most misunderstood deductions for homeowners who work from home. Self-employed individuals and business owners can deduct a portion of home-related expenses — including mortgage interest, utilities, and repairs — based on the percentage of the home used exclusively and regularly for business.

Since the pandemic, more homeowners work from home than ever before. Yet many either overclaim by including spaces that don’t qualify or underclaim by using an overly conservative calculation. If you want a deeper look at the rules, our guide on how to deduct home office expenses if you work from home covers the requirements in full detail.

The “Exclusive Use” Rule Is Non-Negotiable

The IRS requires that a home office space be used exclusively and regularly for business. A kitchen table where you also eat dinner does not qualify. A guest bedroom that doubles as your office does not qualify. The IRS is strict on this, and auditors look specifically for this dual-use scenario.

Many homeowners fail to claim the deduction at all out of fear of audit — which is also a mistake. The audit rate for home office deductions has declined significantly, and a legitimate, well-documented deduction is nothing to fear.

Simplified Method vs. Regular Method

The IRS offers two calculation methods. The simplified method allows $5 per square foot of office space, up to 300 square feet, for a maximum deduction of $1,500. The regular method calculates the actual percentage of your home used for business and applies that to all home expenses — often yielding a much larger deduction.

Homeowners with larger homes and high mortgage interest payments almost always benefit more from the regular method, yet many default to the simplified method simply because it’s easier. That convenience can cost $2,000 or more per year in missed deductions.

Capital Gains Exclusion Errors When You Sell

When you sell your home for a profit, the IRS allows you to exclude up to $250,000 of capital gains if you’re single, or $500,000 if you’re married filing jointly — as long as you’ve lived in the home as your primary residence for at least two of the five years before the sale. This is one of the most generous tax benefits in the entire tax code, yet homeowners routinely fail to maximize it.

The most expensive mistake is failing to track your adjusted cost basis. Your cost basis isn’t just the price you paid for the home — it includes the purchase price plus certain closing costs, plus the cost of any capital improvements made during ownership. Every improvement you fail to document reduces your basis, which means more of your gain becomes taxable.

What Counts as a Capital Improvement

A capital improvement adds value to your home, extends its useful life, or adapts it to new uses. A new roof, an addition, a kitchen remodel, a new HVAC system — these all qualify. Routine maintenance like painting or replacing a broken fixture does not.

Over a 10-year period, a homeowner who keeps meticulous records of $80,000 in improvements has effectively raised their cost basis by $80,000 — potentially saving $20,000 or more in capital gains taxes when they sell, depending on their tax bracket.

The Two-Year Residency Rule Nuances

Many homeowners assume the two-year rule is absolute. In fact, the IRS allows a partial exclusion if you sell before meeting the two-year requirement due to a change in employment, health reasons, or unforeseen circumstances. Homeowners who sell early due to a job relocation often miss this partial exclusion entirely.

Missing Out on Energy Efficiency Tax Credits

The Inflation Reduction Act of 2022 dramatically expanded tax credits for energy-efficient home improvements. Through 2032, homeowners can claim credits worth up to $3,200 per year for qualifying upgrades — yet the ENERGY STAR program estimates fewer than 20% of eligible homeowners claim these credits annually.

There are two main credit programs. The Energy Efficient Home Improvement Credit covers 30% of costs for qualifying improvements like insulation, windows, doors, heat pumps, and electrical upgrades — up to specific annual limits per category. The Residential Clean Energy Credit covers 30% of the cost of solar panels, battery storage, and similar systems with no dollar cap through 2032.

Annual Limits That Reset Every Year

One of the most misunderstood aspects of the Energy Efficient Home Improvement Credit is that many of its limits are annual. You can claim up to $1,200 per year for items like insulation and windows, plus up to $2,000 per year for heat pumps. This means homeowners who strategically stage improvements over multiple years can maximize the credit year after year through 2032.

Homeowners who complete all their upgrades in one year often leave money on the table. Splitting a multi-phase project across two or three tax years can nearly double the total credit captured.

The Product Certification Requirement

Many credits require that the product meet specific energy efficiency certifications. For windows and doors, this means ENERGY STAR Most Efficient designation for some credits. Homeowners who buy products that don’t meet certification requirements — even if they’re high quality — can’t claim the credit. Always check certification before purchasing.

Home Equity Loan and HELOC Deduction Rules

Before 2018, interest on home equity loans and HELOCs was broadly deductible regardless of how the money was used. The Tax Cuts and Jobs Act changed this — and many homeowners are still operating under the old rules, either over-claiming or under-claiming as a result.

Under current law, interest on home equity debt is deductible only if the funds were used to buy, build, or substantially improve the home that secures the loan. If you tapped a HELOC to pay off credit cards or fund a vacation, that interest is not deductible. If you used it to add a bathroom, it is.

Tracking Mixed-Use HELOC Funds

Many homeowners use HELOC funds for a mix of purposes — part home improvement, part other expenses. In that case, you must allocate the interest between deductible and non-deductible portions based on how the funds were actually used. This requires meticulous record-keeping and many homeowners simply guess — or claim all of it, which is incorrect.

The IRS can request records showing the purpose of funds withdrawn from a home equity line. Without documentation, a deduction that was partially legitimate becomes entirely disallowed.

Record-Keeping Failures That Invalidate Deductions

Even when homeowners know about available deductions, poor record-keeping can render them uncollectable. The IRS requires taxpayers to be able to substantiate any deduction claimed — meaning you need receipts, contracts, invoices, or bank records. A deduction you took but can’t prove becomes a liability in an audit.

For homeowners, the most critical records to keep are: closing disclosure documents from purchase and sale, receipts for all capital improvements, Form 1098 statements from each lender, property tax payment receipts, and any contractor invoices for home office or energy efficiency upgrades.

How Long to Keep Homeownership Records

The general IRS rule is to keep tax records for three years from the filing date. But for homeownership records, the guidance is different — and more demanding. You should keep records related to your home’s cost basis for as long as you own the home, plus at least three years after you sell it. That could easily be 20 or 30 years of documentation.

If you haven’t been keeping improvement receipts, start now. Even a partial record is better than none. Contractor estimates, permit applications, and credit card statements can help reconstruct costs if original receipts are lost.

Building good financial habits across all areas of your finances — including documentation — is part of a broader financial health strategy. If you’re working on the fundamentals, our guide on financial goals you should set in your 30s offers a solid framework for getting organized.

The Standard vs. Itemized Deduction Mistake

One of the most consequential homeowner tax deduction mistakes isn’t about a specific deduction at all — it’s about choosing the wrong deduction method. Since the Tax Cuts and Jobs Act nearly doubled the standard deduction (to $14,600 for single filers and $29,200 for married filing jointly in 2024), fewer homeowners benefit from itemizing. But some who should itemize are taking the standard deduction instead.

The break-even point is simple: if your total deductible expenses — mortgage interest, property taxes, charitable contributions, and others — exceed the standard deduction for your filing status, you should itemize. For many homeowners in the first decade of a mortgage (when interest payments are highest) or those in high-tax states, itemizing still wins.

Bunching Deductions to Clear the Threshold

A strategic technique called deduction bunching allows you to alternate between itemizing and taking the standard deduction in different years. For example, you might make two years’ worth of charitable contributions in one year to push your total above the standard deduction threshold, itemize that year, and take the standard deduction the following year.

Homeowners who discover they’re just barely under the itemization threshold may be able to cross it by bunching other deductions — without changing their underlying spending at all. This strategy is legal, effective, and underused.

Don’t Assume Software Always Gets It Right

Most tax software will compare both methods and select the one that produces the lower tax bill. But this only works if you enter all your deductible expenses accurately and completely. If you skip your mortgage interest because you can’t find your Form 1098, the software will default to the standard deduction even if itemizing would have been better.

Garbage in, garbage out — tax software is only as accurate as the data you provide.

Points and Closing Costs You Forgot to Deduct

When you close on a home — whether buying or refinancing — you pay a variety of costs. Some are deductible. Many are not. And homeowners routinely confuse the two, leaving legitimate deductions unclaimed or improperly claiming non-deductible items.

Discount points paid on a purchase mortgage are generally deductible in the year paid, as long as the loan is for your primary residence and the points are a standard practice in your area. Origination fees that are labeled as points but charged for lender services (rather than to reduce the interest rate) are generally not deductible as points — they get added to basis instead.

Closing Costs That Add to Your Basis Instead

Many closing costs that aren’t deductible in the year of purchase still have tax value — they increase your adjusted cost basis, which reduces your taxable gain when you eventually sell. These include transfer taxes, title insurance premiums, recording fees, and legal fees related to the purchase.

Homeowners who throw away their closing disclosure after their first year of ownership lose this basis documentation. Those who keep it and add it to their cost basis could reduce taxable capital gains by thousands when they sell — especially in an appreciating market. This is closely related to the broader habit of tracking your net worth over time, which homeownership plays a major role in.

One area homeowners often overlook while managing closing costs is how hidden or recurring fees quietly erode savings over time. If you’re not already auditing your finances for these kinds of drains, our breakdown of hidden fees that quietly drain your bank account is worth reviewing alongside your tax planning.

Your Action Plan

1. Gather Every Tax Document Before You Start Filing

   Collect your Form 1098 from every lender (primary mortgage, second mortgage, HELOC), property tax payment confirmation, and any settlement statements from home purchases or sales. Don’t start your return until these are physically or digitally in front of you. Missing a single document is how deductions get skipped.

2. Calculate Both Standard and Itemized Deductions Before Choosing

   Add up your mortgage interest, PMI, property taxes (up to the $10,000 SALT cap), and other deductible expenses. Compare that total against the current standard deduction for your filing status. Only decide which method to use after doing this math — not before.

3. Check Box 5 on Every Form 1098 for PMI

   If you pay private mortgage insurance or FHA mortgage insurance premiums, your lender reports it in Box 5 of your Form 1098. Enter this amount in Schedule A, Line 8d. This single step recovers $500–$1,200 per year for homeowners under the income threshold who currently skip it.

4. Document and Claim Qualifying Home Improvements

   Start a dedicated folder — physical or digital — for every home improvement. Keep the contractor invoice, permit, and payment confirmation. This folder serves two purposes: it supports deductions or credits in the current year (for energy efficiency upgrades) and it builds your cost basis for the eventual sale.

5. Review Energy Efficiency Credits for Any Qualifying Upgrades Made This Year

   Check the ENERGY STAR federal tax credit page for a current list of qualifying products and their credit rates. File Form 5695 with your return if you made any qualifying improvements. If you’re planning future upgrades, stage them across multiple tax years to maximize the annual credit caps.

6. Evaluate Your Home Office Deduction Using Both Methods

   If you’re self-employed and use a dedicated space exclusively for business, calculate the deduction using both the simplified method ($5 per square foot, max $1,500) and the regular method (actual expenses multiplied by business-use percentage). Choose the method that produces the larger deduction. Keep a diagram of your home showing the office dimensions as backup documentation.

7. Review Prior Returns for Missed Deductions

   The IRS allows you to file amended returns (Form 1040-X) up to three years after the original return’s due date. If you missed the PMI deduction, energy credits, or points deduction in a prior year, an amended return could recover that money. Recovering $1,500–$3,000 per year across two or three open years is entirely realistic. You may also want to review your broader budget for other uncaptured savings — a subscription audit can reveal additional cash you’re leaving on the table each month.

8. Work with a CPA at Least Once Every Few Years

   Tax software is a tool — it’s only as accurate as what you enter. A CPA or enrolled agent who specializes in individual tax returns can identify deductions you didn’t know to look for, catch errors in your basis calculations, and advise on strategic timing of improvements and sales. The cost ($200–$500 for a typical homeowner return) is almost always recouped in tax savings.

Frequently Asked Questions

Can I deduct mortgage interest if I take the standard deduction?

No. The mortgage interest deduction is an itemized deduction claimed on Schedule A. If you take the standard deduction, you cannot also claim mortgage interest separately. The choice is one or the other — you itemize all eligible deductions, or you take the standard deduction. This is why it’s critical to calculate both options before filing.

How do I know if I should itemize or take the standard deduction?

Add up all your itemizable expenses: mortgage interest (from Form 1098), PMI premiums, property taxes (up to $10,000 combined with state income taxes), charitable contributions, and any other eligible deductions. If the total exceeds your standard deduction amount — $14,600 for single filers or $29,200 for married filing jointly in 2024 — itemizing will save you more money. If it doesn’t, take the standard deduction.

Are home improvement costs ever deductible in the year I pay them?

Generally, no — home improvements increase your cost basis rather than producing an immediate deduction. The exception is improvements that qualify for the Energy Efficient Home Improvement Credit or the Residential Clean Energy Credit, which provide a direct credit (not a deduction) in the year the improvement is installed and paid for. Always check whether a planned improvement qualifies before assuming it’s deductible.

What happens if I sell my home before living in it for two years?

You may still qualify for a partial capital gains exclusion if the sale was due to a qualifying life event — a change in employment, a health condition requiring relocation, or other IRS-recognized unforeseen circumstances. The partial exclusion is calculated as a fraction of the full exclusion based on how long you lived in the home. For example, if you lived there for one year (50% of the two-year requirement), you could exclude up to 50% of the full $250,000 or $500,000 limit.

Is the $10,000 SALT cap permanent?

The $10,000 SALT cap was introduced by the Tax Cuts and Jobs Act of 2017 and is currently set to expire after 2025. Congress could extend it, modify it, or let it expire — which would restore the prior unlimited deduction. Tax planning around the SALT cap should account for the possibility of legislative changes after 2025. Check with a tax professional as year-end approaches for the most current information.

Can I deduct HOA fees on my primary home?

No. HOA fees paid on your primary residence are not deductible for federal income tax purposes. They are deductible, however, if the property is a rental — in that case, they’re treated as an ordinary business expense. Some states may have different rules, so check your state’s guidelines separately.

Do I have to repay energy efficiency tax credits if I sell my home?

Generally, no. Most residential energy credits — including the Energy Efficient Home Improvement Credit and the Residential Clean Energy Credit — do not require recapture if you sell your home. The one exception is the Section 48(E) program for certain larger projects, so verify the specific credit type. Credits claimed in good faith for installed and functioning equipment are typically permanent.

Can I deduct real estate agent commissions when I sell?

Real estate agent commissions are not deductible as a current-year expense. Instead, they reduce the net proceeds from your home sale, which effectively lowers your taxable capital gain. Since you subtract selling costs from your sale price before calculating gain, a $15,000 commission directly reduces your gain dollar-for-dollar. This is worth just as much as a deduction — but only if you account for it correctly on your return.

What if I use part of my home as a rental?

Renting out part of your home creates a mixed-use situation with distinct tax implications. Expenses must be allocated between personal and rental use. The rental portion can generate deductible expenses — including a proportional share of mortgage interest, property taxes, insurance, and depreciation — reported on Schedule E. But this also means the rental portion of your home does not qualify for the capital gains exclusion when you sell. Keeping accurate records is essential to get this allocation right.

Are there homeowner deductions unique to first-time buyers?

There’s no separate federal deduction specifically labeled “first-time homebuyer.” However, first-time buyers often encounter deductions for the first time — including mortgage interest, property taxes, and points paid at closing — and are statistically most likely to miss them. First-time buyers with PMI are also particularly likely to overlook that deduction. If you’re planning your first purchase and thinking about your broader financial picture, understanding sinking funds for large expenses can help you prepare for both closing costs and ongoing homeownership costs.