With just days left in 2025, there’s still time to lower your tax bill — if you act fast.
Thanks to recent tax law updates (including the One Big Beautiful Bill Act), many powerful deductions are stronger than ever this year. Here are 15 of the most commonly missed ones that can save small business owners thousands before the calendar flips to 2026.
1. Bonus Depreciation & Section 179 for Equipment
Buy qualifying equipment, vehicles, or software before year-end and deduct up to 100% immediately (restored full bonus depreciation for assets placed in service in 2025). Section 179 limit is now $2.5 million.
2. Business Mileage
Drive for work? Deduct 70 cents per mile in 2025 — track every trip now to maximize this easy write-off.
3. Home Office Deduction
If you use part of your home exclusively for business, deduct a portion of rent/mortgage interest, utilities, and repairs (simplified method: $5/sq ft up to 300 sq ft).
4. Retirement Contributions
Fund a SEP-IRA or Solo 401(k) by your tax filing deadline (up to 25% of compensation for SEP) — but higher employer matches count for 2025 if set up now.
5. Health Insurance Premiums
Self-employed? Deduct 100% of premiums for yourself, spouse, and dependents.
6. Advertising & Marketing Costs
Every dollar spent on ads, website updates, or promo materials this year is fully deductible.
7. Professional Fees
Bookkeeping, legal, or consulting fees — including what you pay us — are 100% write-offs.
8. R&D Expenses
Immediate full expensing restored for research & development costs incurred in 2025.
9. Startup & Organizational Costs
Newer businesses can deduct up to $5,000 in startup expenses immediately.
10. Business Meals
Deduct 50% (or 100% in some cases) of qualifying meals with clients or team.
11. Education & Training
Courses, workshops, or subscriptions that improve your business skills are deductible.
12. Office Supplies & Software
Everything from paper to QuickBooks subscriptions — buy what you need before Dec 31.
13. Charitable Contributions
Business-related donations (cash or inventory) can lower your taxable income.
14. Qualified Business Income (QBI) Deduction
Up to 20% of your net business income — made permanent, so maximize qualified income this year.
15. Energy-Efficient Improvements
Credits and deductions for upgrades like solar panels or efficient HVAC.
Act Before Midnight Dec 31
These opportunities are strongest in 2025 — some rules tighten in 2026.
Not sure which deductions apply to you or how much you can still save?
Book a free 30-minute call today.
First 10 businesses that book and sign up this month get 10% off their first three months of bookkeeping.
📅 Secure one of the last spots: https://calendly.com/am-onescribebooks/30min?month=2025-12
Don’t leave money on the table — claim what’s yours before 2025 ends.