These are the ten deductions we see overlooked most often, why they get missed, and how to make sure they don't.
1. Mileage
The biggest deduction most owners miss. The 2026 IRS standard mileage rate is 72.5 cents per business mile. For an owner driving 12,000 business miles in a year, that's nearly $8,700 in deductions.
Why it gets missed: most owners don't track mileage as they go. They reconstruct it in March, the IRS doesn't accept reconstructed logs, and the entire deduction is at risk.
How to fix it: use a mileage-tracking app (MileIQ, Stride, Everlance, or similar) that runs in the background and classifies trips as business or personal. The tracking has to be contemporaneous — meaning logged at the time, not after.
2. Home office
If you regularly and exclusively use part of your home for business, you can deduct it. Simplified method: $5 per square foot up to 300 sq ft ($1,500 max). Actual expense method: percentage of home expenses based on square footage.
Why it gets missed: owners worry about audit risk (overblown) or don't realize they qualify. Many owners use a dedicated home office every day and never claim the deduction.
How to fix it: if your space qualifies (regular and exclusive business use), claim it. The audit risk is much smaller than the legend suggests when the space genuinely meets the criteria.
3. Health insurance premiums (self-employed owners)
Self-employed owners can deduct premiums paid for themselves, their spouse, and dependents as an above-the-line adjustment to income — not as an itemized deduction. For a self-employed owner paying $600/month in premiums, that's $7,200 in deductions.
Why it gets missed: self-employed owners often forget it exists, or assume health insurance is "personal" rather than business-related.
How to fix it: tell your CPA exactly what you paid in premiums for the year, including dental and vision if separate. The deduction is limited to net self-employment earnings and you can't claim it if you (or your spouse) were eligible for an employer plan — but most self-employed owners qualify.
4. Self-employment tax (the half-deduction)
If you're self-employed, you pay 15.3% in self-employment tax (the equivalent of both halves of FICA). Half of that is deductible against your income for income tax purposes.
Why it gets missed: it isn't, usually — most tax software and CPAs handle it automatically. But owners doing their own taxes by hand sometimes skip it.
5. Retirement contributions (SEP-IRA / Solo 401(k))
Self-employed owners and small business owners can contribute to retirement plans with much higher limits than personal IRAs:
- SEP-IRA: up to 25% of net self-employment earnings
- Solo 401(k): even higher, combining employee and employer-side contributions
- SIMPLE IRA: lower limits but easier setup
The contributions are deductible, reducing your tax bill while building retirement savings.
Why it gets missed: owners assume retirement planning is "for later" or don't know the higher limits exist for self-employed people.
How to fix it: talk to a CPA or financial advisor before year-end about which plan fits and how much to contribute. Some plans need to be opened by certain deadlines to count for the current tax year.
6. Cell phone (business-use percentage)
If you use your phone for business — even partially — you can deduct the business-use percentage of the bill. For a $100/month phone bill at 70% business use, that's $840/year.
Why it gets missed: it feels small per month, owners don't know the allocation rule, or they don't have a way to document the business-use percentage.
How to fix it: estimate business use honestly (50-80% is typical for owners who use their phone heavily for work) and apply it consistently. Document how you arrived at the percentage.
7. Bank fees, processing fees, and platform fees
Bank account fees, wire fees, merchant processing fees (Square, Stripe, PayPal), and platform fees on contractor payments are all deductible. These often get missed because they're netted out of revenue automatically — your bookkeeping shows the net deposit, not the gross with fees broken out.
Why it gets missed: the fees never appear as their own line item unless your bookkeeping is set up to capture them.
How to fix it: make sure your accounting software is configured to record gross sales and fees as separate transactions, not net of fees. This is a one-time setup fix.
8. Business meals (50%)
Most business meals are 50% deductible — meals with clients, working lunches with the right business purpose, meals while traveling. Many owners don't claim them because they don't keep receipts or don't note the business purpose.
Why it gets missed: receipts get lost, owners don't note who they were with at the time, and tax-time reconstruction can't satisfy IRS documentation requirements.
How to fix it: snap a photo of the receipt at the meal and add a note (who you were with, what you discussed). Most receipt-capture apps make this fast.
9. Subscription services
Software, apps, and subscription services used for business are deductible. The annual cost adds up faster than owners expect:
- Accounting software
- CRM platforms
- Email marketing tools
- Design and creative software
- Cloud storage
- Industry-specific tools
A typical small business runs $200–500/month in subscriptions across all categories. That's $2,400–6,000/year in deductions that hide because each individual line item is small.
Why it gets missed: they're auto-charged, owners forget about them, or they're not categorized cleanly in the books.
How to fix it: review your business credit card statement for recurring charges and make sure each is captured as a deductible business subscription.
10. Professional development
Courses, conferences, books, online learning subscriptions, certifications, and other continuing education that maintain or improve your skills in your current business are deductible.
Why it gets missed: owners think of these as personal investments rather than business expenses, or they pay out of personal accounts and don't reimburse from the business.
How to fix it: pay for professional development from your business account when possible, and make sure those expenses are categorized as continuing education, not generic "office expense."
Bonus: tax-savings categories most owners don't think about
A few that go beyond pure deductions:
- Qualified Business Income (QBI) deduction. Up to 20% of qualified business income for pass-through entities (sole props, partnerships, S-corps, LLCs). Income and business type limits apply.
- Section 179 deduction. Lets you expense equipment immediately instead of depreciating over years. Limits are generous for most small businesses.
- Bonus depreciation. Allows additional immediate expensing on qualifying property. The phase-down schedule has been changing with recent legislation — talk to your CPA about current rules.
These aren't traditional "deductions" — they're tax provisions that significantly reduce your bill if your business qualifies.
How bookkeeping prevents missed deductions
Almost every deduction on this list gets missed for the same reason: the underlying expense wasn't captured in real time, or wasn't categorized in a way that makes it findable at tax time.
Clean monthly bookkeeping fixes this in two ways:
- Expenses get captured as they happen — receipts attached, categories assigned, business purpose noted
- Categories are organized consistently — so when your CPA pulls reports for tax prep, they see every legitimate deduction broken out
The owners who claim every deduction they're entitled to aren't the ones who know the most about taxes. They're the ones with the cleanest books. (More on the bookkeeping side →)
Frequently asked questions
Mileage, by a wide margin. Most owners drive for business throughout the year and either don't track it at all or reconstruct logs at tax time (which the IRS doesn't accept). Using a tracking app from January 1 onward captures the deduction in a way that holds up.
Sometimes. You can amend a tax return going back up to 3 years to claim missed deductions. For deductions like home office or mileage where you have records, it can be worth doing. For deductions where you don't have records, amending isn't realistic.
Claim every deduction you're legitimately entitled to. Don't claim things you're not. The middle ground — "let's see what we can get away with" — is where audit risk lives. Clean records and honest categorization is the right standard.
The legend has outlived the reality. The home office deduction was scrutinized more heavily decades ago. Today, with the simplified method and clearer rules, it's a normal deduction for qualified spaces. The audit risk is overblown.
Where to start
If you're seeing deductions on this list you've never claimed, that's not a tax problem — it's a bookkeeping problem. The deductions exist. The issue is whether your records capture them.
SoFlo360 helps small business owners keep books that catch every deduction throughout the year, so tax time isn't a missed-deduction post-mortem. Spanish-friendly support is available for owners who'd rather handle financial conversations in Spanish.
Book a free consultation or learn more about our bookkeeping services.
This post is educational content, not tax advice. For your specific tax situation, consult a qualified CPA or tax professional.