Year-End Tax Planning Strategies for Small Business Owners
You don't think about taxes in October. You think about them in March, when the numbers are locked, the year is closed, and your CPA is delivering news instead of options. By then the planning window has shut. Almost everything that actually lowers a small business owner's tax bill has to happen before December 31, while you can still change the outcome.
The good news: you have more levers than you think, and a few of them got noticeably better in the last year. Here's how to pull them.
The short answer
Year-end tax planning is the work of intentionally shaping your taxable income before the calendar closes. For most small business owners, the highest-impact moves are buying needed equipment and deducting it immediately, funding a retirement plan that doubles as a tax shelter, timing income and expenses across the December 31 line, and making sure your entity structure isn't quietly costing you. None of it requires exotic loopholes. It requires doing ordinary things on purpose, and on time.
Buy the equipment you actually need, and write it off now
If there's a piece of equipment your business genuinely needs, late in the year is often the smartest time to buy it. Two provisions let you deduct the full cost up front instead of spreading it across years of depreciation.
The first is bonus depreciation. The One Big Beautiful Bill Act, signed into law on July 4, 2025, permanently restored 100% bonus depreciation for qualified property acquired and placed in service after January 19, 2025. That word "permanently" matters: under the old rules, bonus depreciation was phasing down and would have dropped to 40% in 2025, so the planning math changed completely. You can now deduct the entire cost of most qualifying equipment and machinery in the year you put it to work.
The second is Section 179 expensing, which does something similar but with its own rules and caps. The same law raised the Section 179 deduction limit substantially, and for 2026 the cap is $2,560,000, with a phaseout beginning once you place more than $4,090,000 of qualifying property in service (per IRS Rev. Proc. 2025-32). Those are large numbers for most small businesses, which is rather the point: the cap is high enough that you'll almost never bump into it.
Two words do a lot of work in both rules: "placed in service." The deduction is tied to when the asset is actually ready and available for use in your business, not when you ordered it or paid for it. A machine still in its shipping crate on December 31 doesn't count. Buy with enough runway to actually use the thing this year.
Use retirement contributions as a tax shelter that's also yours
Most deductions send money out the door. A retirement contribution sends it into your own account. That's the rare write-off where the money stays in your name, which makes it the first place to look.
If you're self-employed with no employees other than a spouse, a solo 401(k) is usually the most powerful option, because you contribute as both the employee and the employer. For 2026, the employee deferral limit is $24,500, and the total of your employee and employer contributions can reach $72,000 for those under 50. Catch-up contributions push that higher once you're 50 or older. A SEP-IRA is simpler to administer and lets you contribute up to 25% of compensation, also capped at $72,000 for 2026, though it lacks the employee-deferral layer that lets a solo 401(k) reach the max on a lower income.
One timing nuance worth knowing: a solo 401(k) generally has to be established by year-end, even though you have until your filing deadline (including extensions) to fund it. So the account setup is the December deadline; the check can come later.
Time your income and expenses across the line
If your business is on the cash method, which most small service businesses are, you have real control over which year income and expenses land in. The classic move is to accelerate deductible expenses into the current year and defer income into the next: prepay January's software subscriptions in December, stock up on supplies you'll use soon, send a few invoices on January 2 instead of December 28.
This is genuinely useful, with one honest caveat. Deferring income only helps if you expect to be in the same or a lower tax bracket next year. If you're growing fast and next year looks bigger, the textbook advice flips, and you may want to pull income forward into the cheaper year. Strategy follows your actual trajectory, not a rule of thumb.
Don't forget the deduction you don't have to lift a finger for
The qualified business income (QBI) deduction lets eligible pass-through owners deduct up to 20% of their business income. It was scheduled to expire after 2025, and then it didn't: OBBBA made the 20% Section 199A deduction permanent for noncorporate taxpayers. For 2026, the income threshold where limitations begin to phase in is $403,500 for joint filers and $201,750 for single filers. Below those thresholds, the deduction is generally straightforward. Above them, wage and property tests and special rules for service businesses (law, health, consulting, accounting, and the like) start to bite.
You don't "do" anything at year-end to claim QBI directly. But year-end decisions about retirement contributions, equipment, and an S corporation owner's salary all change the income figure the deduction is built on, which is exactly why it belongs in the planning conversation.
What this looks like in real numbers
Say you run a single-member LLC consulting practice, taxed as a sole proprietorship, and you're on track to net $160,000 in 2026. Before year-end, you fund a solo 401(k) and buy a genuinely needed $15,000 of computer and production equipment, placing it in service in December.
Before any moves
Net business profit: $160,000
Year-end moves
Solo 401(k), employee plus employer contributions: about $54,000
Equipment, fully deducted via bonus depreciation: $15,000
Total reduction to taxable income: about $69,000
Result
Taxable income shaped down to roughly $91,000
Approximate federal income tax saved, at a 24% marginal rate: around $16,500
A few honest footnotes, because the clean version is never the whole story. The equipment deduction reduces your Schedule C profit, so it also trims self-employment tax. The retirement employer contribution does not reduce self-employment tax. Your QBI deduction shifts when your income shifts. And your state may not follow the federal bonus depreciation rules at all. The point of the example isn't the exact dollar figure. It's that two deliberate, ordinary decisions in December reshaped the entire year.
Where people get this wrong
The most expensive mistake is buying things purely to "save on taxes." Spending a dollar to save 24 cents is not a strategy, it's a 76-cent loss with a tax-flavored coating. Deductions are a discount on things you were going to buy anyway, not a reason to buy them.
The second is ignoring "placed in service." Owners hear "buy equipment by December 31" and stop listening. If it isn't ready to use this year, the deduction isn't this year's.
The third is treating December as the whole season. The most valuable conversations, especially around entity structure and an S corporation owner's reasonable salary, need to happen in the fall, not the final week, because some of them require paperwork or payroll runs that can't be done retroactively.
And the fourth is forgetting that states go their own way. Many states don't conform to federal bonus depreciation, and some cap or disallow other federal breaks entirely. A move that's brilliant federally can be a wash at the state level, so the analysis has to run both.
The bottom line
Year-end tax planning isn't about clever tricks. It's about making a handful of ordinary decisions deliberately, and making them before the door closes on December 31. Buy what you need and deduct it now, pay your future self through a retirement plan, time your income and expenses to your real trajectory, and make sure your structure is working for you.
The single highest-value habit is simply having the conversation early, while options still exist. If you'd like a second set of eyes on your numbers before the year closes, reach out to us at MashCPA and we'll help you map the moves that actually fit your situation.
