Most small business owners think about taxes in March or April, when the return is due. By that point, the options are limited. You can report what happened. You cannot change much of it.
The decisions that actually affect your tax bill happen earlier, mostly in Q4, and in some cases throughout the year. What you buy, when you buy it, how you compensate yourself, whether you fund a retirement account, and how you time certain income and expenses all have tax consequences that are entirely within your control before December 31 and largely outside your control after it.
This is not about aggressive tax strategies or creative accounting. It is about making deliberate decisions within the rules that already exist, before the window closes.
Before making any year-end moves, you need a current picture of the business’s financial position: revenue and expenses year-to-date, estimated net income for the full year, and a rough projection of what taxable income looks like before any planning.
Without this, year-end tax planning is guesswork. Whether it makes sense to accelerate expenses, defer income, or make additional retirement contributions depends entirely on what this year’s taxable income is likely to be and how it compares to next year.
If you do not have this picture readily available from your books, that is worth addressing before anything else. Clean, current financials are the foundation of any meaningful tax planning conversation.
The post on what financial statements a CEO should review regularly is a good starting point for understanding what your books should be telling you at any point in the year, not just at tax time.
One of the most straightforward year-end strategies is pulling deductible expenses into the current tax year rather than letting them fall into January. If this year’s income is higher than expected or higher than next year is likely to be, recognizing more expenses in the current year reduces this year’s taxable income.
Expenses that can often be accelerated:
Prepaying expenses that will be used in the first few months of next year. Rent, insurance premiums, software subscriptions, and professional service retainers paid in December rather than January shift the deduction into the current year.
Making planned equipment or technology purchases before year-end. If the business was going to buy new computers, office furniture, or machinery anyway, doing it in December rather than January makes the deduction available this year. Under current bonus depreciation rules, a significant portion of qualifying asset costs can be written off immediately.
Paying outstanding vendor invoices before December 31. Expenses that are incurred and paid before year-end are generally deductible in the current year under cash basis accounting.
Funding employee bonuses before year-end. If bonuses for the year are planned, accrual-basis businesses can often deduct them in the year they are accrued even if paid in early January, subject to specific rules. Cash-basis businesses need to pay them before December 31 to take the deduction this year.
The key constraint: expenses need to be genuinely incurred or paid, not just committed to. A purchase order placed in December for goods that will not arrive until February does not generally produce a December deduction.
Understanding whether your business operates on cash or accrual accounting affects which of these strategies apply to you. The post on GAAP vs. cash basis accounting explains how each method treats the timing of income and expenses.
The flip side of accelerating expenses is deferring income, pushing revenue recognition into January if doing so makes tax sense.
For cash-basis businesses, this is relatively straightforward. If a client payment is expected in late December, delaying the invoice or asking whether the client can remit in January shifts that income to next year’s return. This only makes sense if next year’s tax rate is expected to be lower, either because income will be lower or because rates may change.
For accrual-basis businesses, deferral works differently. Revenue is recognized when earned, not when collected, which limits the ability to time it. But there are legitimate scenarios where the timing of completing a project or delivering a final deliverable falls near year-end and can be managed within reason.
Income deferral is not always the right move. If next year looks like it will be equally or more profitable, deferring income simply pushes the tax bill forward without reducing it. The decision requires a projection of both years, not just a look at the current year in isolation.
Retirement plan contributions are one of the most powerful year-end tax tools available to business owners, and the contribution limits for self-employed and small business retirement accounts are considerably higher than most people realize.
A SEP-IRA allows contributions up to 25% of net self-employment income, with annual limits that adjust for inflation each year; the IRS typically announces the updated figure in late October or early November. Regardless of the specific limit, the contribution deadline is one of the more generous ones in the tax code: SEP-IRA contributions can be made as late as the tax filing deadline including extensions, which for most businesses means October 15th of the following year. That flexibility is useful, but decisions about plan establishment and contribution strategy are still worth making before December 31 so you are not scrambling later.
A Solo 401(k) has similar overall limits but requires the employee contribution to be elected by December 31 of the tax year, even though the employer contribution can follow later.
If you do not have a Solo 401(k) in place and want to make employee salary deferrals for the current year, the plan needs to be established before December 31. There’s one exception worth knowing: a sole proprietor with no employees can actually set up the plan as late as the tax filing deadline (without extensions) and still make the employer-side contribution for the prior year, just not the employee deferral piece. It’s a narrower path, but it means missing December 31 isn’t always the dead end business owners assume it is.
SIMPLE IRAs have lower contribution limits but are worth maximizing if one is in place.
For every dollar contributed to a qualifying retirement plan, taxable income drops by a dollar. For a business owner in the 24% bracket, a $20,000 contribution represents $4,800 in federal tax savings, plus potential state tax savings on top of that.
If the business has been planning any significant equipment, technology, or asset purchases, Q4 is the time to evaluate whether doing it before December 31 produces meaningful tax savings.
Section 179 allows businesses to deduct the full cost of qualifying assets in the year of purchase, and the limit for 2026 is $2,560,000; a substantial increase from prior years following the One Big Beautiful Bill Act. For most small and mid-size businesses, that ceiling is unlikely to be a constraint. Bonus depreciation has also been restored to 100% for qualifying property placed in service in 2026, meaning the full cost of eligible assets can be written off immediately rather than depreciated over time. Together, these two provisions make 2026 a particularly favorable year for businesses planning significant equipment or technology investments.
One distinction worth knowing: Section 179 can’t reduce taxable income below zero, so the deduction is capped at the business’s income for the year. Bonus depreciation has no such cap and can create a net operating loss, so for a business with lower income this year, bonus depreciation may be the tool that actually delivers the full write-off, even where Section 179 room runs out.
The practical question is whether a purchase that was going to happen anyway produces a better tax outcome in December versus January. If this year’s taxable income is significantly higher than next year’s, the deduction is worth more now. If the business expects significant growth next year, deferring the deduction might be less valuable than it appears.
Equipment needs to be placed in service, actually in use, before December 31 for the deduction to apply in the current year. Ordered and not yet delivered does not count.
For businesses making capital investments and wanting to understand how those assets flow through the books, the post on setting up a chart of accounts correctly covers how capital expenditures should be recorded and tracked separately from operating expenses.
Year-end is a natural time to ask whether the business is still in the right entity structure. The S-Corp election, for example, needs to be filed within the first two and a half months of the tax year to apply to that year. If the business is currently an LLC and would benefit from S-Corp treatment starting next year, the election needs to be filed by March 15th of that year.
If the business has grown significantly in profitability, or if ownership has changed, or if the growth trajectory suggests institutional capital in the future; any of these are reasons to revisit whether the current structure is still the right fit.
This is not a decision to make quickly, and it should involve both a tax advisor and accounting support. But Q4 is the right time to have the conversation so that any structural changes can be effective from the start of the new year rather than mid-year.
Reconcile Your Books and Get Your Records in Order
Year-end tax planning is only possible with accurate books. If the financials are not current, clean, and reconciled, every estimate and strategy in this post becomes a guess rather than a plan.
Before December 31, it is worth reviewing whether all income has been recorded, whether all deductible expenses are in the books with proper documentation, whether personal and business expenses are cleanly separated, and whether any large transactions from earlier in the year have been properly classified.
Getting this done before year-end also makes the tax preparation process in Q1 significantly smoother and less expensive. Accountants and bookkeepers are in highest demand between January and April. Coming in with clean, organized records shortens the engagement and reduces the cost.
For businesses where the bookkeeping has not been kept current throughout the year, the post on when it makes sense to outsource accounting covers what a structured accounting function looks like and why it pays for itself.
If the business has been making quarterly estimated tax payments throughout the year, Q4 is the time to verify that the total paid is on track to cover the liability.
Underpayment of estimated taxes results in a penalty, regardless of whether the balance is paid in full when the return is filed. The penalty applies to each quarter where the payment was insufficient, which means a year-end catch-up payment does not eliminate penalties for earlier quarters, but it does reduce the total amount owed and limits further exposure.
The fourth quarter estimated tax payment is due January 15th. Running a projection of the full-year liability before year-end gives enough time to adjust that payment appropriately.
What should small businesses do before December 31 for taxes?
At minimum: get a current picture of year-to-date income and expenses, review whether to accelerate deductible purchases or expenses into the current year, maximize retirement account contributions, verify that estimated tax payments are on track, and make sure the books are clean and reconciled. For businesses with significant profitability, reviewing entity structure and talking to a tax advisor before year-end is also worth doing.
Can I deduct expenses I pay in December for services in January?
It depends on your accounting method. Under cash basis accounting, a genuine prepayment of an expense for a service that will be used within the next 12 months is generally deductible in the year it is paid. Under accrual accounting, the deduction typically follows when the expense is incurred, not when it is paid. The IRS has specific rules around prepaid expenses, and large or unusual prepayments get more scrutiny.
When is the deadline to establish a retirement plan for the current tax year?
For a SEP-IRA, the plan can be established and funded as late as the tax filing deadline including extensions, October 15th for most businesses that file an extension. For a Solo 401(k), the plan must be established by December 31 of the tax year, even though contributions can follow later. SIMPLE IRAs must be established by October 1st of the year they are to be effective.
Is it better to accelerate income or defer it at year-end?
It depends entirely on whether your expected tax rate this year is higher or lower than next year. If this year’s income is unusually high and next year is expected to be lower, deferring income makes sense. If next year looks equally or more profitable, deferral just moves the tax bill without reducing it. Running a projection of both years is the only way to make this decision intelligently.
What is bonus depreciation and is it still available?
Bonus depreciation allows businesses to immediately deduct a portion of the cost of qualifying assets rather than spreading the deduction over the asset’s useful life. For 2026, the picture improved significantly: the One Big Beautiful Bill Act restored bonus depreciation to 100% for qualifying property placed in service this year, reversing the phase-down that had been underway. That means businesses can write off the full cost of eligible equipment, technology, and other qualifying assets in the year they are placed in service rather than waiting. The 100% rate was made permanent by the One Big Beautiful Bill Act, so businesses can plan on this treatment continuing rather than timing purchases around an expected phase-down
Should I talk to a tax advisor before year-end?
Yes, for any business with meaningful profitability. The strategies that reduce your tax bill need to be implemented before December 31; a tax advisor cannot retroactively change decisions made in prior months. A Q4 planning conversation with your accountant or CFO, based on current financials, is where most of the real tax savings happen. Waiting until filing season is too late for most of the moves that matter.
The difference between a well-planned year-end and a reactive one shows up in the tax bill. Not dramatically, in most cases, but consistently; and consistently is how it compounds over years of running a business.
None of the strategies here require aggressive interpretation of the tax code. They require knowing the rules, having current financial information to work from, and making deliberate decisions before the calendar year closes. December 31st is a hard deadline. The planning that happens before it determines what options you have. The planning that happens after it determines how you file what already occurred.
Quadrant provides outsourced accounting, controller, and fractional CFO services to businesses, nonprofits, and PE-backed companies. If you want to go into the year-end with a clear financial picture and a real tax plan, we would be glad to talk.
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