When we sit down with a new client — whether it's an agency owner, tech founder, or solo freelancer — we run through their prior year books looking for unclaimed deductions. The result is almost always the same: thousands of dollars left on the table. Not because the rules are obscure, but because nobody tracked the expense when it happened.
Here are the ten we recover most often:
1. Startup costs (up to $5,000 deductible year one)
Pre-launch research, legal entity setup, business registration, training courses. Up to $5,000 can be deducted immediately; the rest amortized over 15 years. Most new founders miss this entirely.
2. Home office (simplified method: $5/sq ft, no receipts)
If a space is used regularly and exclusively for business, it counts. No need to track utilities — the simplified method is $5 per square foot up to 300 sq ft. For a 200 sq ft home office, that's $1,000/year, $12,000 over a decade.
3. Business mileage (must be logged contemporaneously)
Commuting doesn't count. Client visits, supply runs, bank deposits, even driving to a co-working space all do. The IRS mileage rate for 2026 is currently 67¢/mile. Our Business Mileage Log makes this painless.
4. Self-employed health insurance (deductible above the line)
Premiums for you, spouse, and dependents if you're not covered by an employer plan. This reduces your taxable income before calculating self-employment tax — double benefit.
5. Retirement contributions (SEP-IRA, Solo 401k, or SIMPLE)
A profitable solo business can defer 20-25% of net income into a SEP-IRA with zero paperwork. A Solo 401(k) allows even more. Often the single largest deduction we set up for new clients.
6. Software and subscriptions (every single one)
Accounting software, design tools, video conferencing, cloud storage, scheduling apps, Slack, Stripe fees. We typically find $2,000-$8,000/year in subscription expenses that were never categorized as deductible.
7. Professional development (must improve current skills)
Courses, certifications, industry conferences, books. The rule: it has to maintain or improve skills in your current business (not training for a new career). For tech founders and consultants, this is often $5k+/year.
8. Bank and payment processing fees (surprisingly large)
Merchant fees skim 2-3% of card revenue all year. On a $500k agency or SaaS business, that's $10-15k in fees that are 100% deductible — if your books break them out. Most QuickBooks setups don't.
9. Bad debt (accrual-basis only)
If you invoice on accrual basis and a customer genuinely doesn't pay, you can write off the uncollectible invoice. Cash-basis businesses can't use this (they never recognized the income in the first place).
10. Section 179 & bonus depreciation (equipment, vehicles, software)
Buy a computer, camera equipment, or vehicle for business? You can often expense the full cost in the year you place it in service, rather than depreciating it over 5-7 years. Huge for equipment-heavy businesses. Changes yearly, so verify current rules.
The pattern that matters
Every deduction on this list requires one thing: a record kept during the year. You can't remember what you spent on software in March or how many business miles you drove in Q2. Bookkeeping isn't overhead — it's how you keep your own money.
What RR Capital does differently: We don't just file taxes. We review 12 months of transactions, categorize them correctly, flag overlooked deductions, and restructure your books so next year's records are clean from day one.
Want to see what we find? Schedule a tax review or grab our 2026 Small Business Tax Deduction Checklist to audit yourself first.