Every dollar your business spends on a legitimate deduction is a dollar that reduces your taxable income. Yet many small business owners in California and across the country leave thousands on the table each year simply because they do not know what qualifies.
Clear Peak Accounting helps business owners find deductions they have been missing for years. Schedule a tax planning consultation and start keeping more of what you earn.
The 2026 tax year brought meaningful changes, including the permanent restoration of 100% bonus depreciation under the One Big Beautiful Bill Act (OBBBA). Whether you run a tech startup in Santa Monica or a construction company in the Inland Empire, this article walks through the deductions most often overlooked and explains how to claim them correctly.
Home Office Deduction: More Business Owners Qualify Than You Think
If you use a dedicated space in your home regularly and exclusively for business, you likely qualify for the home office deduction. This applies even if you also lease commercial space, as long as you use the home office for administrative tasks or client meetings and have no other fixed location for those activities.
The IRS offers two methods for calculating this deduction:
- Simplified method: Multiply your office square footage (up to 300 square feet) by the IRS-set rate. No depreciation calculations required.
- Actual expense method: Calculate the percentage of your home used for business. If your office takes up 12% of your home, you can deduct 12% of mortgage interest, property taxes, utilities, insurance, and repairs.
The actual expense method often produces a larger deduction for homeowners with higher housing costs, which is common across California. A 200-square-foot office in a home worth $900,000 can generate a meaningful write-off that many owners skip because they assume it is too complicated or risky.
Keep records of your office measurements, utility bills, and mortgage statements. If the IRS questions your deduction, clear documentation makes the difference between keeping it and losing it.
Vehicle Expenses: Choosing the Right Method Matters
Driving to meet clients, visit job sites, or pick up supplies? Those miles are deductible. But vehicle deductions remain one of the most heavily audited areas, and poor record-keeping is the most common reason they get denied.
You have two options:
- Standard mileage rate: The IRS publishes a per-mile rate each year. You multiply your total business miles by that rate. This method covers fuel, maintenance, insurance, and depreciation in a single calculation.
- Actual expense method: Track every cost of operating the vehicle (gas, oil, tires, insurance, repairs, depreciation) and deduct the business-use percentage. If 65% of your driving is for business, you deduct 65% of total vehicle costs.
The standard mileage rate works well for owners who drive frequently and want simplicity. The actual expense method can produce a bigger deduction for owners with newer or more expensive vehicles.
Either way, you need a mileage log. Record the date, destination, business purpose, and miles driven for every trip. Apps like MileIQ or Everlance automate this, but even a spreadsheet works as long as you update it consistently.
What Changed in 2026: Bonus Depreciation and Section 179
One of the biggest developments for 2026 is the permanent return of 100% bonus depreciation. Under the Tax Cuts and Jobs Act of 2017, the bonus depreciation rate had been phasing down: 80% in 2023, 60% in 2024, 40% in 2025, and it was scheduled to drop to 20% in 2026. The One Big Beautiful Bill Act (OBBBA), signed in July 2025, reversed that trend and permanently restored the 100% rate for qualified property acquired after January 19, 2025.
This means you can deduct the full cost of qualifying equipment, machinery, vehicles, and technology in the year you place them in service, rather than spreading the deduction over five to seven years.
Section 179 also remains a powerful option. For 2026, the deduction limit is $2,560,000, with a phase-out beginning at $4,090,000 in total equipment purchases. Unlike bonus depreciation, Section 179 requires an active election and cannot create a net operating loss.
Many business owners combine both strategies: apply Section 179 up to its limit on specific assets, then let bonus depreciation cover the rest. According to the Joint Committee on Taxation, these accelerated depreciation provisions save small businesses billions each year in reduced tax liability.
Need help deciding between Section 179 and bonus depreciation for your equipment purchases? Talk to a Clear Peak Accounting tax advisor to build a strategy that fits your situation.
Retirement Contributions: A Deduction That Pays You Twice
Contributing to a retirement plan reduces your taxable income now and builds long-term wealth. Many small business owners either skip retirement contributions entirely or contribute far less than the law allows.
Here are the most common retirement plan options and their 2026 contribution limits:
| Plan Type | 2026 Employee Contribution Limit | Total Contribution Potential | Best For |
|---|---|---|---|
| SEP-IRA | Employer contributions only | Up to 25% of compensation (max ~$69,000) | Self-employed with few or no employees |
| Solo 401(k) | $23,500 ($31,000 if 50+) | Up to ~$69,000 combined | Self-employed with no employees |
| SIMPLE IRA | $16,500 ($18,500 if 50+) | Up to ~$30,000 with employer match | Small businesses with fewer than 100 employees |
A solo 401(k) is particularly valuable for self-employed professionals because it allows both employee and employer contributions, potentially sheltering over $60,000 from taxes in a single year. If you are over 50, catch-up contributions push that number even higher.
The key detail many owners miss: you can make employee contributions until the tax filing deadline (April 15, or October 15 with an extension), but the plan itself must be established by December 31 of the tax year. Waiting until tax time to set up a Solo 401(k) means you have already missed the window.
Health Insurance Premiums: The Self-Employed Deduction
If you are self-employed and pay for your own health insurance, you can deduct 100% of your premiums for yourself, your spouse, and your dependents. This is an above-the-line deduction, meaning it reduces your adjusted gross income directly, which can also lower your exposure to other phase-outs and surcharges.
The deduction covers medical, dental, and vision insurance premiums, as well as qualifying long-term care insurance premiums (subject to age-based limits).
Two common mistakes to watch for:
- Claiming the deduction when you have access to an employer plan. If you (or your spouse) are eligible for a subsidized employer health plan, you cannot claim the self-employed health insurance deduction for the months you had that option.
- Forgetting to include family members. Premiums for your spouse and dependents under age 27 qualify, even if those dependents are not claimed on your tax return.
For California business owners, state premiums tend to be higher than the national average, making this deduction worth more in dollar terms than it is for businesses in lower-cost states.
Education and Professional Development Write-Offs
Training that maintains or improves skills in your current business is deductible. This includes courses, workshops, conferences, certifications, trade publications, and even online learning subscriptions.
Qualifying expenses include:
- Tuition and enrollment fees for courses related to your industry
- Conference registration, travel, and lodging
- Professional licenses and certification renewals
- Books, trade journals, and industry-specific software training
- Online course subscriptions (LinkedIn Learning, Coursera, industry platforms)
The distinction that matters: the education must relate to your existing business. A real estate broker taking an advanced negotiation course qualifies. That same broker enrolling in medical school does not, because it prepares them for a new career rather than improving skills in their current one.
Many owners also forget that travel expenses to attend conferences are separately deductible. Airfare, hotel, meals (at 50%), and ground transportation to and from a business conference all qualify, as long as the primary purpose of the trip is business-related.
How Do You Deduct Business Marketing and Advertising Costs?
Every dollar you spend to promote your business is deductible as an ordinary and necessary business expense. This includes categories that many owners track poorly or forget to claim:
- Digital advertising (Google Ads, Facebook, LinkedIn, Instagram campaigns)
- Search engine optimization (SEO) services and content creation
- Website hosting, domain registration, and redesign costs
- Business cards, brochures, signage, and printed materials
- Event sponsorships and trade show booth fees
- Email marketing platform subscriptions (Mailchimp, Constant Contact)
The IRS treats marketing costs as fully deductible in the year they are incurred, unlike some capital expenditures that must be depreciated. A $10,000 Google Ads spend in 2026 is a $10,000 deduction on your 2026 return.
One area that trips up business owners: branded merchandise. Promotional items like t-shirts, mugs, or pens with your company logo are deductible as advertising expenses, but gifts to individual clients are capped at $25 per recipient per year.
Business Insurance Premiums Most Owners Forget to Deduct
Premiums for insurance that protects your business are deductible. While most owners remember general liability and property insurance, several other categories often go unclaimed:
- Professional liability (errors and omissions) insurance: Especially relevant for consultants, IT professionals, and service providers.
- Cyber liability insurance: Increasingly common for businesses that handle customer data.
- Business interruption insurance: Covers lost income if your business is temporarily shut down.
- Key person insurance: If your business pays premiums on a policy where the business is the beneficiary, those premiums may be deductible.
- Workers’ compensation: Required in California for businesses with employees, and fully deductible.
Review your insurance policies at year-end. If you added or changed coverage mid-year, update your records so nothing gets missed at tax time.
Not sure which deductions apply to your specific business? Work with Clear Peak Accounting to make sure you are claiming everything you are entitled to.
When Should You Talk to a CPA About Your Deductions?
The best time to review your deductions is before the tax year ends, not during filing season. Year-round tax planning lets you make strategic purchases, adjust retirement contributions, and structure expenses to maximize your deductions while staying fully compliant.
Consider scheduling a tax planning session if any of the following apply:
- Your business revenue grew or declined significantly compared to last year
- You purchased or plan to purchase major equipment or vehicles
- You hired employees or contractors for the first time
- You started working from home or changed your business structure
- You expanded into new states or markets
A qualified CPA can also help you evaluate whether your current business entity structure is still the most tax-efficient option. Many business owners who started as sole proprietors save thousands per year by converting to an S Corporation at the right revenue threshold. Clear Peak Accounting helps California business owners find the right CPA fit for their industry and financial complexity.
Frequently Asked Questions
What are the most commonly missed small business tax deductions?
Home office expenses, vehicle mileage, health insurance premiums for the self-employed, retirement plan contributions, and professional development costs are the deductions most frequently overlooked by small business owners. Many owners also miss marketing expenses, business insurance premiums, and the full scope of equipment depreciation available under Section 179 and bonus depreciation.
Can I deduct home office expenses if I also rent commercial space?
Yes. You can claim the home office deduction even if you have a separate business location, as long as you use the home space exclusively and regularly for business. The IRS requires that the space be your principal place of business for administrative or management activities, or a place where you regularly meet clients.
Did bonus depreciation change for 2026?
Yes. The One Big Beautiful Bill Act (OBBBA), signed in July 2025, permanently restored 100% bonus depreciation for qualified property acquired after January 19, 2025. Before this legislation, the rate was scheduled to drop to 20% in 2026. This means you can now write off the full cost of qualifying equipment in the year it is placed in service.
What is the difference between Section 179 and bonus depreciation?
Both let you deduct equipment costs faster than standard depreciation. Section 179 has a 2026 cap of $2,560,000 and requires you to elect it, but it lets you choose specific assets. Bonus depreciation has no dollar cap and applies automatically to all eligible property, but it can also create a net operating loss. Many businesses use both strategies together for maximum benefit.
How much can I contribute to a Solo 401(k) in 2026?
For 2026, you can contribute up to $23,500 as an employee deferral ($31,000 if you are 50 or older), plus up to 25% of net self-employment income as an employer contribution. The total combined limit is approximately $69,000. The plan must be established by December 31 of the tax year, even though contributions can be made until the filing deadline.
Take Action Before Year-End
Tax deductions only help if you claim them. The most effective approach is to work with an accounting professional throughout the year, not just at filing time. Proactive planning gives you time to make purchases, adjust your retirement contributions, and document expenses before December 31.
Clear Peak Accounting specializes in helping California small business owners identify deductions, structure their finances for tax efficiency, and stay ahead of changing tax laws. Whether you need help with business income tax returns, ongoing accounting and management, or accounting software setup, the team builds strategies around your specific situation.
Contact Clear Peak Accounting today to schedule a tax planning consultation and make sure you are not leaving deductions on the table.